Volume 4, Book 54, Number 505:
Narrated Abu Huraira:
The Prophet said, “When the call for the prayer is pronounced, Satan takes to his heels, passing
wind with noise, When the call for the prayer is finished, he comes back. And when the Iqama is
pronounced, he again takes to his heels, and after its completion, he returns again to interfere
between the (praying) person and his heart, saying to him. ‘Remember this or that thing.’ till the per –
son forgets whether he has offered three or four Rakat: so if one forgets whether he has prayed three
or four Rak’a-t, he should perform two prostrations of Sahu (i.e. forgetfulness).”
Volume 4 – 762 / 1700
SAHIH BUKHARI VOLUME 4 > BOOK 54: BEGINNING OF CREATION