Sunan Abi Dawud 780
Narrated Samurah ibn Jundub:
I remember from the Messenger of Allah (ﷺ) 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."
حَدَّثَنَا ابْنُ الْمُثَنَّى، حَدَّثَنَا عَبْدُ الأَعْلَى، حَدَّثَنَا سَعِيدٌ، بِهَذَا قَالَ عَنْ قَتَادَةَ، عَنِ الْحَسَنِ، عَنْ سَمُرَةَ، قَالَ سَكْتَتَانِ حَفِظْتُهُمَا عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم ‏.‏ قَالَ فِيهِ قَالَ سَعِيدٌ قُلْنَا لِقَتَادَةَ مَا هَاتَانِ السَّكْتَتَانِ قَالَ إِذَا دَخَلَ فِي صَلاَتِهِ وَإِذَا فَرَغَ مِنَ الْقِرَاءَةِ ثُمَّ قَالَ بَعْدُ وَإِذَا قَالَ ‏{‏ غَيْرِ الْمَغْضُوبِ عَلَيْهِمْ وَلاَ الضَّالِّينَ ‏}‏ ‏.‏