Usul al-Kafi
Book 4:
The Book of Divine Proof

Chapter 67
Imamate of Imam al- Husayn (p): the third Imam

427. 3. Imam Muhammad al-Baqir (p) said that just before his death Imam al-Hasan (p) said to Imam al-Husayn (p): O my brother, when I die, turn my face towards the grave of the Prophet Muhammad (p), so that I may renew my allegiance to him. Then turn my face towards the grave of my mother before you bury me in ‘al-Baqi’ (the famous graveyard in Medina)…