Hudhayfah - (رضي الله عنه) - said:
The people used to ask the Messenger of Allaah (صلى الله علیه وسلم) about the good, but I used to ask him about the evil from fear that it would overtake me, so I said: O Messenger of Allaah! We used to bein jaahiliyyah (ignorance) and evil, then Allaah brought this good tous, so is there any evil after this good? He said: “Yes.” I said: And is there any good after that evil? He said: “Yes, but it will be tainted.” I asked: What will taint it? He said: “A people guiding others with other than my Sunnah, you will approve of some (of their actions) and disapprove of others.” I asked: Then is there any evil after that good? He said: “Yes! Callers to the Gates of Hell-Fire, whoever responds to them in that will be thrown into it.” I said: O Messenger of Allaah! Describe them to us. He said: “They will be from our own people and speak our language.” I said: What do you order me to do if that should happen in my own lifetime? He said: “Stick to the Jamaa’ah (united body) of the Muslims and their Imaam.” I said: What if they do not have a united-body nor an Imaam? He said: “Then keep away from all those sects even if you have to bite upon the root of a tree, until death overtakes you and you are in that state.” 
So this is a very great and important hadeeth, since it contains: “A very clear statement of fact connected to the present condition of the Muslims today, since they do not have an established Jamaa’ah (united- ody), nor an Imaam who has the bay’ah (pledge of allegiance). Rather, they are split into separate parties which differ in their thoughts and their systems also. So this hadeeth shows that the Muslim, in the like of this situation, should not take part in joining the parties, nor unite with any group or sect - as long as the Jamaa’ah which has at its head an Imaam having the pledge of allegiance of all the Muslims is not present.” 
Al-Haafidh Ibn Hajar (d.856H) explains in Fathul-Baaree (13/35) the chapter heading given by al-Bukhaaree for this hadeeth, so he said:
“And it means: What should the Muslim do in the state of disunity before there is ijmaa’ (consensus) upon a Khaleefah?”
“And the wording of the hadeeth clearly shows that the conversation between Allaah’s Messenger sal-Allaahu 'alayhe wa sallam and Hudhayfah - (رضي الله عنه) was about unity and disunity with regards to the political field. And the final question (asked by Hudhayfah) totally applies to the new situation that has occurred in the Islaamic world at the end of the ’Uthmaanee Khilaafah and after its collapse.
So the answer obligates sticking to obedience to the Ameer (leader) and joining together under his banner. However, if the state is reached where there is no longer any Ameer and each one is pleased with his own opinion, then it is obligatory to avoid all the groups and sects who struggle with one another to attain the position of Ameer (leader) and authority - and their only aim is authority, and they have no clear ’aqeedah ... However, if a just Muslim Imaam appears, then it is obligatory to align behind him. So here, the vileness of what the political parties are based upon is clear. Since, the order is to stick to the Jamaa’ah and the Imaam, and to stay clear of all the sects - however much hardship that causes. It also shows the vileness of hizbiyyah (partisanship) and splitting into groups formed upon the basis of race, nationalism, territory, language, and their like - and upon the basis of differences in ’aqeedah (beliefs) and Islaamic rulings. So this hadeeth gives us a firm standpoint for the situation in this age in which we live.” 
Thus, what is binding upon the Muslim is:
“To avoid all (such) people, even if it means biting upon a root of a tree until death overtakes him. This is better for him than entering into a group having no Imaam, for fear of what this will lead to - corruption through differing desires and forsaking opinions.” 
Imaam Ibn Jareer at-Tabaree (d.310H) said:
“And the hadeeth shows that when a people do not have an Imaam, and the people split into parties, then no one is to be followed in that state of disunity - avoiding all of them if possible - for fear of falling into evil.” 
Since in disunity there is a resemblance to the people of Jaahiliyyah (pre-Islaamic ignorance) who:
“Did not have an Imaam to unite them upon a Deen and a single view, and their Deens (religions and ways of life) were varied.” 
And Allaah - the Most Perfect has rendered the people of Islaam above this, throughout the ages and differing conditions.
Here, there are two further points to be noted:
 What Imaam ash-Shaafi’ee (d.204H) - (رحمه الله) - said in his book Ar-Risaalah (nos.1319-1320), about sticking to the Jamaa’ah of the Muslims:
“If their Jamaa’ah is spread out through the lands, then no one can stick to a body of people who are separate. It may also be that the people found together are composed of Muslims and kaafirs (unbelievers), and pious and wicked - so then there would be no meaning to uniting bodily since it is not possible, and also because uniting into a mass of bodies does not produce anything.
So sticking to their Jamaa’ah would not have any meaning, except sticking to what their Jamaa’ah is agreed upon, with regards to what is halaal (lawful) and haraam (prohibited), and obedience in that. So whosoever says what the Jamaa’ah says has stuck to them, and whosoever opposes what the Jamaa’ah of the Muslims says, has opposed their Jamaa’ah which he was ordered to cling to. And error occurs in disunity, but as for the Jamaa’ah, then it is not possible for all of them to be in error about the meaning of a text of the Book, the Sunnah, or qiyaas (correct analogy) - if Allaah wills.”
Because of this, ’Abdullaah ibn Mas’ood - (رضي الله عنه) - said his well-known golden saying, referring to the absence of the Jamaa’ah of the Muslims:
“The Jamaa’ah is whatever agrees to the truth, even if you are alone.” 
So there is no place for parties, disuniting and transformations. Rather, there has to be a coming together upon the correct manhaj (methodology), and a rallying around the Straight Path and the clear and guided way.
 No one should think that our showing the hadeeth to be a forbiddance of separate parties means that we say:
“That work should not be done to bring about Islaamic life and to create a society ruled by Allaah’s Laws. Rather, these things are the fruits of following the way of guidance - even if those who follow it are few. So what is considered is the one who speaks the truth, not the one who merely speaks first; and also the quality, not merely the quantity.” 
So his sal-Allaahu 'alayhe wa sallam’s saying:
“Even if you have to bite upon the root of a tree.”
So, in order to bite to the root of a tree, then this does not mean that you have to stay at a distance from the Muslims, or abandoning ordering the good and forbidding the evil, and totally avoid the Muslims, as some of them - without right - think!! Rather, that is not true, since the word lau “if” in the Arabic language  necessitates here: avoidance of something, in order to avoid what is contrary to it. Since quite often withholding from joining the sects and the parties - which is what has been ordered to avoid and keep far away from does not involve biting upon the root of a tree. Therefore, the meaning is:
“If keeping away from those sects can only be done by biting (on the root of a tree), then that is what must be done.” 
This is due to the severity of what this involves.
The order to remain aloof refers to the places of trials and disunity, and that it in no way implies that you leave:
“The Ummah of Islaam and its obligatory function, with which Allaah sent down His Books and sent His Messengers: ordering good - and the greatest of that is Tawheed, and forbidding the evil - the worst of which is Shirk. This being established upon knowledge, controlling the self with objectivity, being filled with mildness, patience and certainty.” 
Not as is the situation with our Ummah today, since:
“We are afflicted with those who push themselves forward in giving da’wah to Allaah - the Most Perfect, the Most High - and make lawful political assassinations and barbaric rabble-rousing, and seeking help against falsehood with further falsehood.”
So by this they negate the noble duty and lofty task, whilst thinking that they are doers of good!!
 This is the title of a chapter given by Imaam al-Bukhaaree in his Saheeh (13/35).
 Related by al-Bukhaaree (no.7084) and Muslim (no.1847).
 From the words of our Shaikh al-Albaanee - (رحمه الله) - on a cassette-tape from the series: Silsilatul-Hudaa wan-Noor (no.200/1) compiled by our brother Muhammad Aboo Laylaa.
 Al-Ahzaabus-Siyaasiyah (p.88) of Shaikh Safiur-Rahmaan al-Mubaarakpooree.
 ’Umdatul-Qaaree (12/193) of Imaam Badrud-Deen al-’Aynee.
 Ibn Hajr quotes it from him in Fathul-Baaree (13/37) and agreed to it.
 Al-’Uzlah (p.58) of Imaam Abu Sulaymaan al-Khattaabee.
 Reported by Imaam al-Laalikaa‘ee in Sharh Usool Ahlus-Sunnah wal-Jamaa’ah (no.160).
 Mu’allafaat Sabd Hawwaa Diraasatan wa Taqweeman (p.170) of Saleem al-Hilaalee.
 See Mayaman-Naboo (p.315) of ’Abdul-Ghanee ad-Daqr.
 ’Umadatul-Qaaree (24/194) of al-’Aynee.
 Hukmul-Intimaa (p.91) of Shaikh Bakr Aboo Zayd.