As mentioned by Imam Sadiq (as)...

As mentioned by Imam Sadiq (as), “Become an ornament for us, do not be a disgrace for us.”[^3] And his statement that: “Call the people [to your religion] without using your tongue.”[^4] In Usool Kafi through correct chains of narrators it is narrated from His Eminence, Abu Abdullah Imam Sadiq (as) that he said: I don’t consider anyone as a believer unless he follows us in all matters, pay attention that indeed, among our demands are piety and abstemiousness; so decorate yourself with it so that the Almighty Allah send mercy to you and through the abstemiousness you put your enemies in sorrow and grief so that the Almighty Allah gives you honor and keep you alive.[^5] In Rauda Kafi, it is narrated from Imam Ja’far Sadiq (as) that he said: I and Abu Ja’far [Imam Baqir (as)] passed a group of Shias who were sitting between the Prophet’s grave and his pulpit.

I said to His Eminence, Abu Ja’far: They are your Shias and devotees, may I be sacrificed on you. He replied: Where are they? I said: I saw them between the grave and the pulpit. He said: Take me to them. So we went to them and saluted them. Then the Imam said: By Allah, I love your fragrance and your souls, help us with abstemiousness and struggle as whatever is with the Almighty Allah is not achieved except through abstemiousness and struggle.

And since He makes the servant know his Imam he follows him. Indeed, by Allah, you all are on my religion, and the religion of my forefathers Ibrahim and Ismail, and since they were on this religion, so you help this religion through abstemiousness and struggle.[^6] Allamah Majlisi, in the explanation of this tradition says: The Imam has mentioned the names of Ibrahim and Ismail to show that all prophets are following him in religion.

Or it could also be the fact that they were progenitors of the Holy Prophet (S) and his family which goes on to show that the Prophet and his family follow the right faith and the prophets follow them. Thus ‘they’ indicate Ibrahim and Ismail and the other past prophets (as). And these include his forefathers from the Prophet (S) and the Holy Imams (as).