Musannaf Ibn Abi Shayba 3:610

Ibn Fudayl narrated to us, from Khusayf, from Abu Ubaydah, from Abdullah, who said: The Messenger of Allah (may Allah bless him and grant him peace) taught me the Tashahhud: "At-tahiyyatu lillahi, was-salawatu wat-tayyibatu. As-salamu 'alayka ayyuhan-nabiyyu wa rahmatullahi wa barakatuhu. As-salamu 'alayna wa 'ala 'ibadillahis-salihin. Ashhadu an la ilaha illallah, wa ashhadu anna Muhammadan 'abduhu wa rasuluhu." (Greetings are for Allah, and prayers, and good things. Peace be upon you, O Prophet, and the mercy of Allah and His blessings. Peace be upon us and upon the righteous servants of Allah. I bear witness that there is no god but Allah, and I bear witness that Muhammad is His servant and His messenger.)