Sahih Al Bukhari Hadith Number 830

Narrated `Abdullah bin Malik bin Buhaina: Once Allah’s Messenger (peace be upon him) led us in the Zuhr prayer and got up (after the prostrations of the second rak`a) although he should have sat (for the Tashahhud). So at the end of the prayer, he prostrated twice while sitting (prostrations of Sahu).

10  Call to Prayers (Adhaan)
Hadith number 830
Volume no 1
Chapter: 147 ((Saying of the) Tashah-hud in the first sitting.)