Abu Dawud Book 2, Hadith Number 779.

Narated By Samurah ibn Jundub : I remember from the Apostle of Allah (PBUH) two periods of silence. Sa’id said: We asked Qatadah: What are those two periods of silence? He said: (one) when he began his prayer, and (one) when he finished the recitation. Then he added: When he finished reciting (the closing verse of the Fatihah): “Not of those with whom Thou art angry, nor of who go astray.”