Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.131B.

‘Ali related that a slave, who had agreed on terms of his freedom with his master, came to him and said, “I cannot pay my master as I agreed in the terms of freedom, so help me.” ‘Ali said to him, “Let me teach you the supplication that the Prophet, peace be upon him, taught me. If you say it, Allah will cause your debt to be paid even if it be as great as a mountain. Say, ‘O Allah, make Your lawful bounties sufficient for me so as to save me from what is unlawful, and from Your grace grant me sufficient abundance to make me free from the need of all except You’.” (Reported by Tirmizhi, who considers it sound)

Abu Sa’id al-Khudri reported, “One day the Prophet, peace be upon him, entered the mosque. He saw there a man from the Ansar called Abu Umamah. He asked, ‘What is the matter with you that I see you sitting in the mosque when it is not the time of prayer.’ He replied, ‘I am very much worried and in great debt, O Messenger of Allah!’ The Prophet said, ‘Let me teach you words to say so that Allah will remove your worries and settle your debt?’ He exclaimed, ‘Of course, O, Messenger of Allah.’ The Prophet said, ‘Say in morning and evening, “O Allah, I seek refuge in You from all worry and grief. I seek refuge in You from incapacity and slackness. I seek refuge in You from cowardice and niggardliness, and I seek refuge in You from being overcome by debt and being subjected to men”.’ The man said, ‘When I did that, Allah removed all my worries and settled my debt’.” (Abu Daw’ud)