Sahih Bukhari

Narrated Abu Rafi`:Once I prayed the `Isha' prayer with Abu Huraira and he recited, ""Idha s-samaa'u n-shaqqat"" (84) and prostrated. I said, ""What is that?"" He said, ""I prostrated behind Abul-Qasim, (the Prophet) (when he recited that Sura) and I will go on doing it till I meet him