Sunan Ibn Majah, Chapter: The Chapters on Expiation

that his father Abu Musa said: "I came to the Messenger of Allah (saw) with a group of Asharites and asked him to give us animals to ride. He said: 'By Allah, I cannot give you anything to ride, and I have nothing to give you to ride.' We stayed as long as Allah willed, then some camels were brought to him. He ordered that we be given three she-camels with fine humps. When we left, we said to one another: 'We came to the Messenger of Allah (saw) to ask him for animals to ride, and he swore by Allah that he would not give us anything to ride, then he gave us something. Let us go back.' So we went to him and we said: 'O Messenger of Allah! We came to you seeking mounts, and you took an oath that you would not give us mounts, then you gave us some mounts.' He said: 'By Allah, I did not give you animals to ride, rather Allah gave you them to ride. I, by Allah, if Allah wills, do not swear and then see something better than it, but I offer expiation for what I swore about, and do that which is better.' Or he said: 'I do that which is better and offer expiation for what I swore about.'"