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

Chapter 30
Adherence to the right path

361. 2. Imam Jafar as-Sadiq (p) was asked about the words of God: Those who say, Our Lord is God and are resolute, then no fear shall grip them, nor shall they grieve (Q, 41:30).
The Imam (p): Those who are loyal to the Imam, one after the other will be visited, continuously, by the angels announcing, ‘…Fear not, nor grieve but rejoice in the paradise that you have been promised’ (Q, 41:30).