Musannaf Ibn Abi Shayba 21:478

Abdullah ibn Numayr narrated to us, Musa ibn Muslim al-Tahan narrated to us, from Abd al-Rahman ibn Sabit, who said: There was a group of people who were brothers [in faith]. He said: They missed a man among them for some days, then he came to them. They said: "Where were you?" He said: "A debt that was upon me." He said: "Why did you not call upon these supplications: 'O Reliever of every distress, O Remover of every worry, O Discloser of every grief, O Answerer of the supplication of the distressed, O Most Merciful of the world and the Hereafter and their Most Merciful One, You are my Most Merciful, so have mercy upon me, O Most Merciful, with a mercy that makes me independent of the mercy of anyone other than You.'"