Hisham bin 'Urwa هشام بن عروة · The Book of Forgetfulness (In Prayer)

"The Messenger of Allah (ﷺ) used to teach us the tashahhud just as he used to teach us a surah from the Quran."

After saying the taslim the Messenger of Allah (ﷺ) would say: "Allahumma anta as-salam wa minka as-salam tabarakta ya dhal-jalali wal-ikram (O Allah, You are the source of eace (or the One free from all faults) and from You comes peace, blessed are You, O Possessor of Majesty and Honor)."