صحيح البخاري

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."