Hudhayfah (may Allah be pleased with him) narrated, “Whenever the Prophet (peace be upon him) read a verse about Allah’s punishment, he would seek refuge in Allah. And whenever He read a verse mentioning Allah’s mercy, he would ask Allah for His mercy.” (Ahmad, 6/24, Abu Dawood, no. 873, and others; graded Hasan by Al-Albani)

Sheikh Abdul Aziz Bin Baz said: It’s Sunnah for every Muslim who reads the Qur’an – during prayer or elsewhere – to ask Allah for His bounty at the verses of mercy; and to seek refuge from the Hell-fire when he reads about Allah’s punishment. Furthermore, when a Muslim reads a verse that deems Allah above something, he declares it by saying, “Subhanahu wa Ta’ala.”

It’s recommended for every Muslim who reads “Is not Allah the Best of judges?” (Qur’an, 95:8) to say, “Indeed! I believe that to be true.” When one reads, “Is not He (Allah Who does that) Able to give life to the dead?” (Qur’an, 75:40), he should say, “Indeed! I bear witness to this.”

When one reads, “Then in what statement after this (the Qur’an) will they believe?” (Qur’an, ), he should say, “I believe in Allah.” (Qur’an, 77:50)

After the slave recites the verse, “Then which of the Blessings of your Lord will you both (jinns and men) deny? (Qur’an, 55:13), he should say, “We don’t deny any verses from our Lord.” And after reading, “Glorify the Name of your Lord, the Most High,” (Qur’an, 87:1), he says, “Subhana Rabbiyal A’la.”

All these acts are recommended for the Imam, followers, or a person reciting the Qur’an. These words are du’a. They resemble saying “Ameen” after Fatihah, and Ameen should be said in prayer and elsewhere after reciting Fatihah.

(Majmoo Fatawa Bin Baz, vol. 26, p. 62-63)
– Translated by Abdullah Bin Dwight Battle