Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.044A.

It is allowed for the imam or the one praying individually to recite “‘ayyah of sajdah” during the salah, even if the recital is audible (jahriyyah) or inaudible (siriyyah), and he should prostrate, during the salah, after reading such ‘ayat. Al-Bukhari and Muslim record from Abu Raf’i who said: “I prayed salatul ‘isha with Abu Hurairah and he recited Izhas-sama’u un-shaqqat [al-Inshiqaq] and he prostrated during the prayer. I asked: ‘O Abu Hurairah, what prostration is this?’ he said: ‘I made a prostration when reciting (this surah) behind Abu al-Qasim (Prophet), and since then I never stopped making a sajdah whenever I recite it.”‘ Al-Hakim relates, from Ibn ‘Umar, with a sound chain that meets the criteria of al-Bukhari and Muslim, saying that the Prophet sallallahu alehi wassalam made a sajdah during the first rak’ah of the noon prayer and his companions were of the opinion that he had recited surah as-Sajdah.

An-Nawawi says: “It is not disliked for the imam to recite ‘ayat of sajdah, according to our school, or for the one who prays individually. And it does not matter if the recital is audible or inaudible. And he should make sajdah after he recites them.”

Malik holds: “In general it is disliked.” Abu Hanifah’s opinion is that: “It is disliked during the silent recitals but not during the audible recitals.” The author of al-Bahr maintains: “According to our school, it is preferred to delay the sajdah until after he [the imam] makes the taslim in order not to confuse the people praying behind him.”