So here are some authentic sayings reported from them, as examples of their living and clear actions. So if we take some examples from the level of the Companions, we find that which brings delight to the heart of one who seeks to follow his Messenger (صلى الله علیه وسلم), whilst also refuting the opinion of the innovators:
'Abdullaah ibn Mas'ood (رضي الله عنه) said:
"Follow and do not innovate, for you have been given that which is sufficient [and every innovation is misguidance]." 
'Abdullaah ibn 'Umar (رضي الله عنه) said:
"Every innovation is misguidance, even if the people consider it to be something good." 
And if we look at their actions we will see that they were in total agreement with their sayings:
So 'Amr ibn Salamah narrated:
We used to sit at the door of 'Abdullaah ibn Mas'ood before the morning Prayer, so that when he would come out we would walk with him to the mosque. One day Abu Moosaa al-Ash'aree came to us and said: Has Abu 'Abdur-Rahmaan (i.e. Ibn Mas'ood) come out yet? We replied: No! So he sat down with us until he came out. When he came out we all stood along with him, so Abu Moosaa said to him: O Abu 'Abdur-Rahmaan! I have just seen something in the mosque which I deemed to be evil, but - and all praise is for Allaah - I did not see anything except good. Ibn Mas'ood inquired: "What did you see?" Abu Moosaa replied: If you live, you too will see it. In the mosque I saw people sitting in circles awaiting the Prayer. In each circle they had pebbles in their hands and a man would say: repeat Allaahu Akbar a hundred times. So they would repeat it a hundred times. Then he would say: repeat Laa ilaaha illallaah a hundred times. So they would repeat it a hundred times. Then he would say: repeat Subhaanallaah a hundred times. So they would say it a hundred times. Ibn Mas'ood then asked: "What did you say to them?" Abu Moosaa said: I did not say anything to them. Instead I waited to hear your view, or what you declared. Then we went along with him, until he came to one of these circles and stood up and said: "What is this I see you doing?" They replied: O Abu 'Abdur-Rahmaan! These are pebbles upon which we are counting takbeer, tahleel and tasbeeh. He said to them: "Rather, count up your evil deeds. For I assure you that none of your good deeds will be lost. Woe be to you O Ummah of Muhammad sallallaahu 'alayhi wa sallam! How quickly you head into destruction! These are the Companions of your Prophet sallallaahu 'alayhi wa sallam and who are widespread. There are his clothes which have not yet decayed, and his bowl which is unbroken. By Him in whose Hand is my soul! Either you are upon a religion better guided than the Religion of Muhammad sallallaahu 'alayhi wa sallam, or you are opening the doors of misguidance." They said: O Abu 'Abdur-Rahmaan! By Allaah! We only intend good. He said to them: "How many there are who intend good, but do not achieve it. Indeed Allaah's Messenger sallallaahu 'alayhi wa sallam said to us: "A people will recite the Qur'aan, but it will not pass beyond their throats." By Allaah I do not know, but perhaps most of them are from you." Then he left. Amr ibn Salamah said: We saw most of those people fighting against us on the day of Nahrawaan, alongside the Khawaarij. 
So this excellent narration encompasses many great principles, which are not known except to those who follow the Messenger (صلى الله علیه وسلم), those who do not put anything before Allaah and His Messenger, but rather say: We hear and we obey.
So from the principles are:-
Firstly: That the One who prescribed the ends, did not Forget to prescribe the means. So when Allaah prescribed For His servants the dhikr (rememberance of Allaah), He did not forget to prescribe the means and the way to do this. So Allaah's Messenger (صلى الله علیه وسلم) used to count the tasbeeh (glorifications of Allaah) upon his right hand  and he said that they (i.e., the fingers) will he questioned and would speak. 
Secondly: That al-bid'ah al-idbaafiyyah is misguidance. And al-bid'ah al-idbaafiyyah is: that type of innovation which is based upon a proof with regards to its foundation, but it has no proof with regards to the manner or the form. That is why it is called idbaafiyyah (something added on). And this type of innovation is, from one angle, directly against correct guidance, and from another angle, it is in agreement with it. So these people did not say something which is kufr (disbelief), nor did they do something which was in itself evil, rather they were remembering Allaah - and this is something which is prescribed by Revelation. However, the manner in which they performed this action went against the guidance laid down by Muhammad (صلى الله علیه وسلم), and so the Companions opposed them and told them to count this amongst their evil actions instead.
Thirdly: Allaah - the Most Perfect, the Most High - is not to be worshipped, except by what He prescribes. So He is not to be worshipped according to desires, customs or innovations.
Fourthly: That innovations kill off the Sunnah. So this group of people innovated a new way of performing dhikr (remembering Allaah), which was not reported from Allaah's Messenger (صلى الله علیه وسلم). So in doing this, they killed off the guidance of Muhammad (صلى الله علیه وسلم). And this is a principle which the Salafus-Saalih (Pious Predecessors) well understood, and they knew for certain that innovations and the Sunnah cannot unite together:
Hassaan ibn 'Atiyyah (d.120H)- (رحمه الله) - said:
"No people introduce an innovation into their religion, except that its like from the Sunnah is ripped away from them." 
Fifthly: That innovations are the cause for destruction, since it leads to abandoning the Sunnah, and this causes tremendous misguidance. The noble Companion 'Abdullaah ibn Mas'ood (رضي الله عنه) said:
"If you were to abandon the Sunnah of your Prophet then you would go astray." 
So if the Ummah goes astray then it is destroyed. Therefore 'Abdullaah ibn Mas'ood said to that group:
"O Ummah of Muhammad (صلى الله علیه وسلم)! How quickly you head into destruction."
So the particular relevance of Ibn Mas'ood's understanding is reflected in the context of the above narration. So Abu Moosaa al-Ash'aree (رضي الله عنه) did not criticise them, rather he waited for the view or the order of 'Abdullaah ibn Mas'ood (رضي الله عنه). And this stance was not merely taken out of love or out of displaying false affection to Ibn Umm 'Abd (i.e. to Ibn Mas'ood). Rather Abu Moosaa was pleased for himself with what Allaah's Messenger (صلى الله علیه وسلم) was pleased with for his Ummah, since he (صلى الله علیه وسلم) said:
"I am pleased for my Ummah with what Ibn Umm 'Abd is pleased with for it." 
Also in the narration is a proof that all of the Companions were agreed in opposing this action, since 'Abdullaah ibn Mas'ood (رضي الله عنه) used as a proof the fact that the Companions (رضي الله عنهم) were wide spread (and therefore could easily be asked).
Sixthly: Innovations quickly lead to kufr (disbelief). This is because the innovator has set himself up as one who is able to legislate and prescribe things; and thus set himself up as a partner to Allaah, adding things to the rulings laid down by Allaah, thinking that he is on a religion of better guidance than the Religion of Muhammad (صلى الله علیه وسلم).
Seventhly: That innovations open the doors widely for disagreements to occur, and this is a door to misguidance. So whosoever lays down an evil way in Islaam, then he bears the sin of it and the sin of those who act upon it, until the Day of Judgement, without their sin being reduced by anything. And this is because the one who guides to an evil action is like the one who does it.
Eighthly: Not giving importance to the matter of shunning innovations, leads to evil and sins. Do you not see that these people came to be amongst the ranks of the deviated group called the Khawaarij on the day of Nahrawaan, fighting against the Companions (رضي الله عنهم), who were led by the Leader of the Believers 'Alee (رضي الله عنه), who cut-off this deviated group, on that memorable day.
Imaam al-Barbahaaree (d.329H)- (رحمه الله) - said:
"Beware of small innovations, because they grow and become large. This was the case with every innovation introduced into this Ummah. It started as something small, bearing a resemblance to the truth, which is why those who entered into it were misled, and then were unable to leave it. So it grew and it became the religion which they followed, so they deviated from the Straight Path and thus left Islaam. May Allaah have mercy upon you! Examine carefully the speech of everyone you hear from, in your time particularly. So do not act in haste, nor enter into anything from it, until you ask and see: Did any of the Companions of the Prophet (صلى الله علیه وسلم) speak abou t it, or any of the (early) Scholars? So if you find a narration from them about it, cling to it and do not go beyond it for anything, nor give precedence to anything over it and thus fall into the Fire." 
Ninthly: Righteous actions are only according to righteous intentions, and a good intention does not make something which is futile correct. This is because intentions alone cannot make an action correct, but rather complying with the Sharee'ah (Prescribed Laws) must be added to that. 
Finally: Adding to something good is not good, because addition in good is evil, and this is something that is witnessed in everything. Thus, a matter, when it goes beyond its limits, changes to its opposite. So bravery, when it is added to, turns into rashness, and if it is decreased from , then it becomes cowardice. And generosity, if its limits are exceeded, then it becomes wastefulness, and if it is fallen short of, then it becomes miserliness. So the best of the affairs are the justly-balanced ones.
And 'Abdullaah ibn Mas'ood (رضي الله عنه) was not alone amongst the Companions in condemning innovations. So here we find 'Abdullaah ibn 'Umar (رضي الله عنه), who was one of severest from the Companions in condemning innovations and abandoning the innovators. So once he heard a man sneezing and saying: Praise be to Allaah and may the salaah and salaam (the praises of Allaah and blessings of peace) be upon Allaah's Messenger. So he said to him: What is this? This is not what Allaah's Messenger (صلى الله علیه وسلم) taught us, rather he said: "When one of you sneezes then let him praise Allaah. " And he did not say: And also send salaah (blessings of peace) upon Allaah's Messenger. 
Likewise was the practice of the Taabi'een (those who met the Companions and clung to their way). So in this regard there is what is reported from Sa'eed ibn al-Musayyib (d.90H) (رحمه الله), that he saw a man praying after the appearance of dawn, more than two rak'ahs, making many rukoos (bowings) and sajdahs (prostrations), so he forbade him from this. So the man said: O Abu Muhammad (i.e. Ibn al-Musayyib)! Will Allaah punish me for my Prayer? So he said: "No! But He will punish you for opposing the Sunnah (Prophetic guidance)." 
And these narrations contain many good points of benefit, so from them:-
 The Companions rebutting everyone who went against the authentic Sunnah, sometimes being very severe in their rebuttal, even if it was against their own fathers and sons.
 That bid'ah at-tarkiyyah is misguidance: And this type of bid'ah (innovation) is one for which there is a proof to establish the action, except that the people deliberately leave the action, thinking that it is a part of the Religion, or something similar to it. For example, some of the Soofees who abandon marriage in order to emasculate themselves. The proof for this being misguidance is from Allaah - the Most High's - saying:
"O you who Believe! Do not make haraam (unlawful) the good things that Allaah has made halaal (lawful) to you, and do not transgress. Indeed Allaah does not love the transgressors. And eat of the things that Allaah has provided for you, lawful and good, and have taqwaa (fear and obedience) of Allaah in Whom you believe." [Soorah al-Maa'idah 5:87-88]
So this aayah (verse) is concerned with a single meaning, which is: making forbidden that which Allaah has allowed from the good and pure things, and doing so as a matter of religion. And Allaah has forbidden this, and considered it as going beyond the limits, since it is transgressing upon Allaah's right, in that He alone has the right to prescribe and legislate. And Allaah does not love those who transgress the limits. Then Allaah affirmed the allowance of these things with an even greater emphasis by His saying:
"And eat of the things that Allaah has provided for you, lawful and good, and have taqwaa (fear and obedience) of Allaah in Whom you believe." [Soorah al-Maa'idah 5:87-88]
Then he ordered them to have taqwaa (piety and obedience to Him). So this shows that the forbiddance of what Allaah has made lawful, in any form, is outside the bounds of taqwaa. Therefore, the Messenger (صلى الله علیه وسلم) said to those three men who came to the houses of the Prophet (صلى الله علیه وسلم), asking about his worship and then on being informed about it, considered their own worship to be very little, so they said: What a great difference there is between us and the Prophet (صلى الله علیه وسلم), whose previous and latter sins have been forgiven by Allaah. So one of them said: I will always Pray during the night. The other one said: I will always fast during the day and not break my fast. And the third of them said: I will keep away from women and never get married. Then Allaah's Messenger came to them and said:
"Are you the people who said such and such? By Allaah! I am the one who is the most knowledgeable about Allaah amongst you, and the one who has the most taqwaa of Him. Yet I fast and break my fast, I pray and I sleep, and I marry women. So whosoever turns away from my Sunnah (guidance) is not from me." 
So if the Companions (رضي الله عنهم) left for us words of deep insight and which clearly enlighten the hearts, then men after them, who likewise attained the truth from this light, have also left for us words which are almost like the words of the Companions. And this is because they were those who very closely followed in the footsteps of the Companions - and the likes of their sayings have already preceded. However we add here a final example of their stance of truth:
Thus, a man came to Imaam Maalik (d.179H) - (رحمه الله) - and said:
O Abu 'Abdullaah! Where shall I enter the state of ihraam (the dress for one intending to do Pilgrimage)? So Imaam Maalik replied: "From Dhul-Hulayfah, where Allaah's Messenger (صلى الله علیه وسلم) entered the state of ihraam." The man then said: But I wish to enter the state of ihraam at the mosque by his grave. So Imaam Maalik said: "Do not do that, for I fear for you the fitnah (trial)." So the man said: What fitnah are you referring to, since it is only a few extra miles: So Imaam Maalik said: "And what fitnah can be greater than for you to think that you have attained some virtue, which Allaah's Messenger sallallaahu 'alayhi wa sallam fell short of. Have you not heard the saying of Allaah:"Let those beware who oppose the command of the Prophet sallallaahu 'alayhi wa sallam, lest they are afflicted with fitnah (trial), or lest they are afflicted with a painful punishment." [Soorah an-Noor 24:63]." 
 Related by Wakee' on az-Zuhd (no.315) and Abu Khaythamah in Kitaabul-'Ilm (no.54), where al-Albaanee authenticated it. The addition is related by at-Tabaraanee in al-Kabeer (9/154) and it is authentic.
 Related by al-Bayhaqee in al-Madkhal ilas-Sunan (no.191) and also Ibn Nasr in as-Sunnah (p.24). Its isnaad (chain of narration) is as authentic as the sun!
 Related by ad-Daarimee in his Sunan (1/79), at-Tabaraanee in al-Kabeer (9/126) and Abu Nu'aym in Hilyatul-Awliyaa (4/381). It was authenticated by al-Haythamee in Majma'uz-Zawaa'id (1/181).
 Saheeh: Related by Abu Daawood in his Sunan (no.1502), from 'Abdullaah ibn 'Amr (رضي الله عنه). It was authenticated by al-Albaanee in Saheeh Sunan Abee Daawood (1/280).
 Hasan: Related by Abu Daawood in his Sunan (no.1501), from Yusairah radiallaahu 'anhaa. It was authenticated in Saheeh Sunan Abee Daawood (1/280).
 Related by ad-Daarimee (1/45) and it is authentic.
 Related by Muslim (5/156).
 Saheeh: Related by al-Haakim (3/317-318) and Ibn 'Asaakir in al-Majlis (no.350). It was authenticated by al-Albaanee in as-Saheehah (no.1225).
 Sharhus-Sunnah (no.8).
 Refer to Madaarijus-Saalikeen (1/85) of Ibn al-Qayyim.
 Related by at-Tirmidhee (no.2738) and al-Mizzee in Tahdheebul-Kamaal (no.552-553). The isnaad is good.
 Related by al-Bayhaqee is as-Sunanul-Kubraa (2/466) and the isnaad is authentic.
 Related by al-Bukhaaree (9/104) and Muslim (9/175).
 Related by Imaam ash-Shaatibee in al-I'tisaam (1/132).