We prostrated ourselves along with the Messenger of Allah (ﷺ) on account of: "When the sky is rent asunder" and "Recite in the name of Your Lord Who created"
Sunan Abi Dawud Book 7, Hadith 7
← Previous Hadith The Messenger of Allah (ﷺ) recited Surah al-Najm and prostrated himself. No one remained there who did not prostrate (along with him). A man from the people took a handful of pebbles or dust and raised it to his face saying: This is enough for me. 'Abd Allah (b. Mas'ud) said: I later saw him killed as an infidel.

Sunan Abi Dawud Book 7, Hadith 6 Next Hadith → I offered the night prayer behind Abu Hurairah. He recited Surah Inshiqaq ("When the sky is rent asunder") and prostrated himself. I asked him: What is this prostration ? He replied: I prostrated myself on account of this (surah) behind Abu al-Qasim (i.e. the Prophet). I shall continue prostrating on account of this till I meet him.

Sunan Abi Dawud Book 7, Hadith 8