Al-Adab al-Mufrad

Saeed bin Abu Burdah says that I heard my father narrate that Abdullah bin Umar (may Allah be pleased with them both) saw a man from Yemen performing Tawaf of the Ka'bah, and he had his mother on his back, and he was reciting these verses: "I am a trained camel for my mother; if her mounts are frightened, I will not be frightened." Then he asked Ibn Umar (may Allah be pleased with them both): What do you think, have I repaid my mother? He said: No, not even for a single breath (of her labor). Then Ibn Umar (may Allah be pleased with them both) performed Tawaf and, coming to Maqam Ibrahim, offered two rak'ahs and said: O son of Abu Musa! Every two rak'ahs become an expiation for the sins committed before them.