At that time, perhaps Hazrat Ali (radhiyallahu ‘anhu) did not possess any wealth. Therefore, he did not offer him any financial assistance. Rather, he responded saying, “Shall I not teach you some words (of du‘aa) which Rasulullah (sallallahu ‘alaihi wasallam) taught to me? These words are such that even if the debt upon you is as great as the Mountain of Seer (the name of a certain mountain), Allah Ta‘ala will still settle the debt for you?”

Hazrat Ali (radhiyallahu ‘anhu) then taught him the following du‘aa:

اَللّٰهُمَّ اكْفِنِيْ بِحَلَالِكَ عَنْ حَرَامِكَ وَأَغْنِنِيْ بِفَضْلِكَ عَمَّنْ سِوَاكَ

O Allah! Suffice me with Your halaal (sustenance and wealth), from that (sustenance and wealth) which You have declared as haraam (unlawful for me), and make me independent, through Your special grace and favor, from everyone besides You.

(Sunan Tirmizi #3563)