Why did the Prophet Muhammad (saw) stand up for the third rak'a without sitting for Tashah-hud and perform two prostrations before ending the prayer with Taslim?
 Narrated `Abdullah bin Buhaina Al-Asdi:                     (the ally of Bani `Abdul Muttalib) Allah's Apostle stood up for the Zuhr prayer and he should have sat (after the second rak`a but he stood up for the third rak`a without sitting for Tashah-hud) and when he finished the prayer he performed two prostrations and said Takbir on each prostration while sitting, before ending (the prayer) with Taslim; and the people too performed the two prostrations with him instead of the sitting he forgot.