Sahih Muslim Book 4, Hadith Number 1246.

Chapter : Excellence of Dhikr after prayer and its description.

Abu Huraira reported that when the Messenger of Allah (may peace be upon him) stood up for the second rak’ah he opened it with the recitation of the praise of Allah, the Lord of universe (al-Fatiha), and he did not observe silence (before the recitation of al-Fatiha).