Jami` at-Tirmidhi 292
جامع الترمذي#292SahihWa'il bin Hujr said:"I arrived in Al-Madinah and I said, 'Let me look at the Salat of Allah's Messenger.' When he sat - meaning for At-Tashah-hud - he spread his left foot, and placed his left hand - meaning on his left thigh - and held his right foot erect
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 2:144