Answer: Praise to Allaah.
What is correct is to make it neither too long nor too short. Making it so long that it causes hardship to people is not allowed. When the Prophet (صلى الله علیه وسلم) heard that Mu’aadh ibn Jabal (رضي الله عنه) was making the prayers too long for his people, he spoke to him angrily in a manner that he had never used when advising someone and said to Mu’aadh:
“O Mu’aadh, are you putting people off?” [Bukhaaree, al-Adaab, 6106; Muslim, as-Salaah, 465]
What the Imaam should do is to adhere to the Sunnah.
Undoubtedly making the du’aa’ too long causes hardship to the people and exhausts them, especially those who are weak. Some people may have work to do, or they may not want to finish before the Imaam but it is difficult for them to stay with the Imaam. So we advise our brother Imaams to follow a moderate course, and to omit the du’aa’ sometimes so that the people will not think that the du’aa’ is obligatory.