Sahih Muslim Book 27, Hadith 12
We were sitting in the company of Abu Musa that he called for food and it consisted of flesh of fowl. It was then that a person from Banu Tamim visited him. His complexion was red having the resemblance of a slave. He said to him: Come and (join me in food). He showed reluctance. He (Abu Masa) said: Come on, for I saw Allah's Messenger (ﷺ) eating it (fowl's meat), whereupon that person said: I saw it eating something (of filth and rubbish) and I found it repugnant and took an oath that I would never eat that. He (Abu Muds) said: Come, so that I would narrate to you about that (the incident pertaining to vow). (And he narrated thus): I came to Allah's Messenger (ﷺ) along with a group of people belonging to the tribe of Ash'ari, asking him to provide us with riding camels. He (the Holy Prophet) said: By Allah, I cannot provide you with riding animals. And there is nothing with me with which I can provide you a mount. We stayed (for some time) there as Allah willed, and there was brought to Allah's Messenger (ﷺ) booty of camels. He called us and commanded that we should be given five white humped camels. As we were about to go back, some of us said to the other: As we made Allah's Messenger (ﷺ) forget oath, there would be no blessing for us (in his gift). We went back to him and said: Allah's Messenger, we came to you to provide us with riding animals and you took an oath that you would never equip us with mounts and then you have provided us with the riding beasts Allah's Messenger, have you forgotten? Thereupon he said: I swear by Allah that if Allah so wills, I shall not swear an oath, and then consider something else to be better than it without making atonement for my oath and doing the thing that is better. So you go; Allah, the Exalted and Glorious, has given you riding animals.
My friends sent me to Allah's Messenger (ﷺ) asking him to provide them with mounts as they were going along with him in jaish al-'Usrah (the army of destitutes or of meagre means or army setting out during the hard times and that is the occasion of the expedition of Tabuk) I said: Apostle of Allah, my friends have sent me to you so that you may provide them with mounts. He (the Holy Prophet) said: By Allah, I cannot provide you with anything to ride. And it so happened that he was at that time much perturbed. I little knew of it, so I came back with a heavy heart on account of the refusal of Allah's Messenger (ﷺ), and the fear that Allah's Messenger (ﷺ) might have some feelings against me. I returned to my friends and informed them about what Allah's Messenger (ﷺ) had said. I had hardly stayed for a little that I heard Bilal calling: 'Abdullah b. Qais. I responded to his call. He said: Hasten to Allah's Messenger (ﷺ), he is calling you, When I came to the Prophet (ﷺ) he said: Take this pair, this pair, and this pair (i. e. six camels which he had bought from Sa'd), and take them to y, our friends and say: Verily Allah (or he said: Verily Allah's Messenger (ﷺ) has provided you with these animals. So ride upon them. Abu Musa said: I went along with them to my friends and said: Verily Allah's messenger (ﷺ) has provided you with these animals for riding; but by Allah, I shall not leave you until some of you go along with me to him who had heard the talk of Allah's Messenger (ﷺ) then I asked him for you, and his refusal for the first time, and then his granting them to me subsequently; so you should not think that I narrated to you something which he did not say. They said to me: By Allah, in our opinion you are certainly truthful, and we would do as you like. So Abu Musa went along withsome of the menfrom them until they came to those who had heard the words of Allah's Messenger (may, peace be upon him) and his refusal to (provide) them with (animals) ; and subsequently his granting (the animals) to them; and they narrated to them exactly as Abu Masa had narrated to them.
This hadith has been narrated on the authority of Abu Musa al-Ash'ari with a slight variation of words.