Zahdam narrates from Abu Musa al-Ash'ari (may Allah be pleased with him): We came to the Messenger of Allah (peace and blessings be upon him) asking for mounts. He (peace and blessings be upon him) said: "By Allah! I will not give you mounts, nor do I have any mount with which to provide you." But when we went back, he (peace and blessings be upon him) gave us three camels. I said: You (peace and blessings be upon him) had sworn that you would not give us mounts, yet you (peace and blessings be upon him) then gave us mounts. He (peace and blessings be upon him) said: "I did not give you mounts; rather, Allah gave you mounts. By Allah! whenever I swear an oath and see something else to be better, I do the better thing."
The Shaykh said: Al-Taymi fell short in this narration and did not transmit the expiation in it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 19844