The Hadith is in Bukhari and in Muslim, Muttafaq Alaihi, after Rasulullah Sallallahu Alaihi Wasallam, he taught us the Tahiyat in the Hadith of the Tahiyat, at the end of the Hadith.
After you finish the Tahiyat, after you finish the salat ala Rasulullah Sallallahu Alaihi Wasallam, many people, innaka Hamidun Majid, Assalamu Alaikum Warahmatullah, Assalamu Alaikum Warahmatullah.
So Rasulullah Sallallahu Alaihi Wasallam used to say, "Allahumma inni a'udhu bika min adhabi jahannam, wa min adhabi al-qabr, wa min fitnatil mahya wal mamat, wa min sharri fitnatil Masih ad-Dajjal."
"Allahumma inni zalamtu nafsi zulman kathira, wa la yaghfirudh dhunuba illa anta, faghfirli maghfiratan min indika warhamni innaka antal Ghafurur Rahim."