Sahifah Hammam ibn Munabbih

And the Messenger of Allah, peace and blessings be upon him, said: "When the call to prayer (adhan) is made, Satan turns his back and flees, passing wind loudly so that he does not hear the sound of the adhan. When the call to prayer is finished, he returns. Then, when the iqamah for prayer is pronounced, he again turns his back and flees. When the iqamah is finished, he comes back and puts thoughts into the heart of the worshipper and says, 'Remember such-and-such, remember such-and-such,' things which he had not remembered before, until the worshipper does not remember how many (rak‘ahs) he has prayed."