Reference: Sharh ‘Umdatil-Fiqh – Tape 1, Question No.15
Question: Some of them say the origin of the first [part of the] tashahhud is that when the Messenger (sal-Allaahu ‘alayhi wa sallam) ascended to heaven, he began by extending the salaam to his Lord, and said:
«التَّحِيَّاتُ لِلهِ وَ الصَّلَوَاتُ وَ الطَّيِّبَاتُ»
…and [in response], Allaah (‘Azza wa Jall) said to His Prophet:
«السَّلامُ عَلَيْكَ أَيُّهَا النَّبِيُّ»
…[and so on] to the end?
Response: By Allaah, I have not seen this. This is the first time I am hearing this. I have not seen this. Whoever it is that says this – if he has a reference then let him share it with us; tell us ‘I found it in such-and-such a book’.