(28) باب الأَخْذِ بِالْيَدَيْنِ
Narrated Ibn Mas`ud:
Allah's Messenger (ﷺ) taught me the Tashah-hud as he taught me a Sura from the Qur'an, while my hand was between his hands. (Tashah-hud was) all the best compliments and the prayers and the good things are for Allah. Peace and Allah's Mercy and Blessings be on you, O Prophet! Peace be on us and on the pious slaves of Allah, I testify that none has the right to be worshipped but Allah, and I also testify that Muhammad is Allah's slave and His Apostle. (We used to recite this in the prayer) during the lifetime of the Prophet (ﷺ) , but when he had died, we used to say, "Peace be on the Prophet."
Reference: Sahih al-Bukhari 6265
In-book reference: Book 79, Hadith 39
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 74, Hadith 281