مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 961
Prayer
Making Mention of God after the Prayer - Section 1
وَعَنْ ثَوْبَانَ رَضِيَ اللَّهُ عَنْهُ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا انْصَرَفَ مِنْ صَلَاتِهِ اسْتَغْفَرَ ثَلَاثًا وَقَالَ: «اللَّهُمَّ أَنْتَ السَّلَامُ وَمِنْكَ السَّلَامُ تَبَارَكْتَ يَا ذَا الْجلَال وَالْإِكْرَام» . رَوَاهُ مُسلم
Thauban said that when God’s Messenger finished his prayer he asked forgiveness three times and said, “O God, You are Peace, and peace comes from You. Blessed are You, O Possessor of glory and honour.” Muslim transmitted it.
Mishkat al-Masabih, 961صَحِيح (الألباني)