Jami At Tirmidhi
292
Sahih+3

Wa'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

SahihAhmad Muhammad Shakir
SahihAl-Albani