Authentic Supplication Number 134.

It is reported of ‘Ali bin ‘Abi Talib  that someone who was indebted came to him and said: I am unable to pay my debt so help me. He said: Shall I not teach you a few words the Messenger of Allah  taught me, if you had the like of a mountain (Seerin) of debt Allah would fulfill it on your behalf? Say: ‘Allahumma kfinee bihalalika `an haramika, wa ‘aghninee bifadhlika `amman siwaka (156).

(156) O’ my ‘ilah make me with what You have made lawful needless of what You have made unlawful, and make me with your benevolence independent of all others.

Reported by At-Tirmidhi who said it was comely (hasan). Al-Albani agreed, and included this hadeeth in The Authentic of Good Sayings as #116.