Who gave dawah to Uthman bin Mazun (ra) ?

In a reply to Imam Ali (as) naming his children after the 3 calipahs, the 12er reply to one of the points by quoting this tradition.

Abul Faraj Isfahani (d.356) records in Maqatilut Tallbiyyin in Vol 1 page 23 and Allamah Majlisii in Bihar al Anwar in vol 45 page 38 Imam Ali a.s said: "I named my son on the name of my brother, Uthman bin Mazun"

Okay let's accept this as a fact. Now my question is who gave dawah to Uthman bin Mazun? The answer is simple. It was the 1st Calipah Abi Bakr