The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 798
Ibn 'Abbas reported: The Messenger of Allah (may peace be upon him) used to teach us tashahbud just as he used to teach us a Sura of the Qur'an, and he would say: All services rendered by., words, acts of worship. and all good thirgs are due to Allah. Peace be upon you,0 Prophet. and Allah's mercy and blessings. Peace be upon us and upon Allah's upright servants. I testify that there is no god but Allah, and I testify that Muhammad is the Messenger of Allah. In the narration of Ibn Rumb (the words are):" As he would teach us the Qur'an."