Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 776
Narated By Samurah ibn Jundub : I remember two period of silence in prayer, one when the imam said the takbir; and one when he finished reciting the Fatihah and the surah when he was about to bow. But Imran ibn Husayn took it as something strange. So they wrote about it to Ubayy (ibn Ka'b) in Medina. He verified the statement of Samurah.