Musannaf Ibn Abi Shayba 3:605

Abu Bakr narrated to us, he said: Husayn bin Ali narrated to us, from al-Hasan bin al-Hurr, from al-Qasim bin Mukhaymirah, he said: Alqamah took my hand and said: Abdullah took my hand and said: The Messenger of Allah (may Allah bless him and grant him peace) took my hand, teaching me the Tashahhud: "The greetings (at-tahiyyat) are for Allah, and the prayers (as-salawat), and the good things (at-tayyibat). 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."