Confirmed Prophetic traditions:
*Tawarruk* during the final *tashahhud*.
On the authority of Abu Humayd al-Sa'idi (may Allah be pleased with him), who said:
When the Messenger of Allah (peace and blessings of Allah be upon him) sat during the final rak'ah,
he would tuck his left foot under and keep his right foot upright,
and sit directly on his posterior.