"I heard Abū Başīr asking Abū 'Abdillah ('a.s.) and said to him: 'May I be made your ransom! Inform me about the religion which Allah, to Whom belong Might and Majesty, made incumbent upon the servants [al-'ibād] that it is not allowed for them to remain ignorant of it, and it will not be accepted from them beside that. What is that [religion]?' He ['a.s.] said: 'Repeat it [the question] for me.' So, I repeated it for him. He ['a.s.] said: 'Bearing witness that there is no god but Allah and that Muhammad (ş.a. 'a.w.a.) is the Messenger of Allah, performing the ritual prayer, giving the alms, making pilgrimage to the House if he is able to make his way there and fasting during the month of Ramadan.'
Then he ['a.s.] was silent for a bit. Then he said: 'And al-wilāyah,' twice. He ['a.s.] then said: 'This is what Allah had made incumbent upon the servants, and the Lord will not question the servants, on the Day of Reckoning, saying: "Why did you not add to what I had made incumbent upon you?' But whoever adds to that, Allah [s.w.a.] will increase His reward for him. Surely, the Messenger of Allah (s.a. 'a.w.a.) had prescribed certain good and sanctified practices, that people are ought to take hold of them.""
— Usul al-Kāfī
