Praise be to Allah.
It is Sunnah for the imam to straighten the rows himself, or to tell the congregation to straighten the rows. A variety of expressions are narrated in the Sunnah, all of them telling the worshippers to straighten the rows, and warning them against doing otherwise. Among the phrases that have been narrated are: “Straighten the rows and stand close together” and “Straighten your rows, for straightening the rows is part of establishing prayer” and “Straighten your rows for straightening the rows is part of perfecting the prayer” and “Straighten the rows in prayer for straightening the rows is part of doing the prayer well” and “Stand straight and do not make the rows uneven, lest that that create disharmony amongst you” and “Straighten the rows and stand shoulder to shoulder and fill the gaps” – and other such phrases.
There is no need to say any of these or other phrases if the imam sees that the rows are straight.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said:
But if the imam turns round and sees that the rows are straight and solid (with no gaps), and the people are standing in straight rows, then it seems that he should not tell them to straighten the rows, because that has been done – unless he intends thereby to tell them to keep it like that – because these words have a meaning, they are not just words that are to be said for no purpose.
As’ilat al-baab il-Maftooh, no. 62.
We do not know of any phrase in the Sunnah with which the imam may encourage the worshippers to focus more in their prayer and focus their hearts on Allaah and the prayer, as if it were their last prayer and so on. If the imam always says that then there is the fear that it may come under the heading of bid’ah (innovation). There is nothing wrong with saying such things as a reminder but that should be done sometimes, not all the time and in every prayer.
We know of no basis for saying “Focus your hearts on Allaah”. With regard to the phrase “Pray like a man bidding farewell,” there is a saheeh report that the Prophet (peace and blessings of Allaah be upon him) said this, but that was by way of general advice, not what the imam should say before saying the first takbeer of the prayer.
It was narrated that Abu Ayyoob said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “When you stand to pray, pray like a man bidding farewell. Do not say anything for which you will have to apologize. And give up hope for what other people have.”
Narrated by Ibn Maajah, 4171. Classed as saheeh by Shaykh al-Albaani in al-Silsilah al-Saheehah, 401.
And it was narrated that Ibn ‘Umar said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Pray like a man bidding farewell as if you can see Him, for although you cannot see Him, He sees you, and do not be concerned about what other people possess, then you will live a rich life. Beware of any action that requires an apology.”
Narrated by al-Bayhaqi in Kitaab al-Zuhd (The Book of Asceticism), 2/210.
It is saheeh because of the existence of corroborating reports, as Shaykh al-Albaani said in al-Silsilah al-Saheehah, 1914.