Musnad Ahmad 788:263

Yazid ibn Harun narrated to us, he said: Sulayman—meaning al-Taymi—informed us, from Abu al-Sulayl, from Zahdam, from Abu Musa, who said: We came to the Messenger of Allah (peace and blessings of Allah be upon him) seeking mounts from him. He said: "No, by Allah, I will not provide you with mounts." When we returned, the Messenger of Allah (peace and blessings of Allah be upon him) sent to us three camels with white-spotted humps. I said: The Messenger of Allah (peace and blessings of Allah be upon him) swore that he would not provide us with mounts, then he provided us with mounts. So we came to him and said: O Messenger of Allah, you swore that you would not provide us with mounts, yet you provided us with mounts. He said: "I did not provide you with mounts, but Allah provided you with mounts. By Allah, I do not swear an oath and then see something else better than it, except that I come to that which is better." Abu Abd al-Rahman said: My father said: Abu al-Sulayl is Darib ibn Nuqayr.