Musnad Ahmad 3854
Musnad of Abdullah bin Mas'ood
It was narrated that Ibn Mas'ood (رضي الله عنه) said: The Messenger of Allah (ﷺ) was taught all that is good and how to attain it. We did not know what to say in prayer until he taught us and said: "At-Tahiyyatu Lillahi was-salawatu wat-tayyibatu. As-salamu ‘alaika ayyuhan-Nabiyyu wa rahmatullahi wa barakatuhu. As-salamu ‘alaina wa 'ala 'ibadillahis-saliheen. Ashhadu an la ilaha illallah wa ash-hadu anna Muhammadan abduhu wa rasooluh (All compliments, prayers and pure words are due to Allah. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us and upon the righteous slaves of Allah. I bear witness that there is no god except Allah and I bear witness that Muhammad is His slave and Messenger).”