صَحِيحُ مُسْلِمٍ
Sahih Muslim 591
The Book of Mosques and Places of Prayer
It is recommended to recite statements of remembrance after the prayer, and how that is to be done
حَدَّثَنَا دَاوُدُ بْنُ رُشَيْدٍ، حَدَّثَنَا الْوَلِيدُ، عَنِ الأَوْزَاعِيِّ، عَنْ أَبِي عَمَّارٍ، - اسْمُهُ شَدَّادُ بْنُ عَبْدِ اللَّهِ - عَنْ أَبِي أَسْمَاءَ، عَنْ ثَوْبَانَ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا انْصَرَفَ مِنْ صَلاَتِهِ اسْتَغْفَرَ ثَلاَثًا وَقَالَ اللَّهُمَّ أَنْتَ السَّلاَمُ وَمِنْكَ السَّلاَمُ تَبَارَكْتَ ذَا الْجَلاَلِ وَالإِكْرَامِ . قَالَ الْوَلِيدُ فَقُلْتُ لِلأَوْزَاعِيِّ كَيْفَ الاِسْتِغْفَارُ قَالَ تَقُولُ أَسْتَغْفِرُ اللَّهَ أَسْتَغْفِرُ اللَّهَ .
Thauban reported: When the Messenger of Allah (ﷺ) finished his prayer. He begged forgiveness three times and said: O Allah! You are Peace, and peace comes from You; Blessed are You, O Possessor of Glory and Honour. Walid reported: I said to Auza'i: How is the seeking of forgiveness? He replied: You should say: I beg forgiveness from Allah, I beg forgiveness from Allah."
Sahih Muslim, 591Sahihصحيح