The Prophet ﷺ, when he finished his prayer with the salam, would say, "O Allah, You are Peace, and from You comes peace. Blessed are You, Possessor of Majesty and Honor."
حدثنا مسلم بن إبراهيم حدثنا شعبة عن عاصم الأحول وخالد الحذاء عن عبد الله بن الحارث
أن النبي ﷺ كان إذا سلم قال اللهم أنت السلام ومنك السلام تباركت يا ذا الجلال والإكرام
Muslim narrated it in the Book of Mosques, chapter on the recommendation of remembrance after prayer and its description, hadith 592, from the hadith of Shubah with this chain.