The first proof of the Imām’s walāyat, friendship and love, is the verse: “Verily, your walī is Allāh and His Messenger and those who believe and establish prayer, and give zakāt while they are in rukū (bowing down).” (5:55). During the time of revelation, nobody had given zakāt in the state of rukū, nor is there an explicit injunction to give this special zakāt. It was only an accident that Mawlā ʿAlī was in the state of rukū when a poor man begged and the Imām gave him his ring. Thus, referring to this event, his walāyat has also been incumbent in addition to that of God and the Prophet. Now, with respect to the question of why this meritorious deed of the Imām is mentioned in the plural form, the answer is that Mawlā ʿAlī is the father of the Imāms, therefore, in his word and deed are included all those holy Imāms who are going to come to this world till the Resurrection, as it is said about Ḥaz̤rat Ibrāhīm: “Verily, Ibrāhīm was an ummat (nation) obedient to Allāh, by nature upright.” (16:120).
This excerpt has been taken from page 14