Praise be to Allah,
[Muhammad] ibn Abu ‘Adiyy narrated to us from Humayd [at-Taweel] from Anas ibn Maalik who said,
“Abu Moosaa [al-Ash(aree] asked the Prophet (PBUH) to provide him [and some of his other companions] with a mount, but he was busy with something else [that angered him] so much that he (PBUH) said, ‘By Allah, I will not provide you with a mount.’ When Abu Moosaa turned to leave, he (PBUH) called him and gave him a mount. Abu Moosaa said to him, ‘Messenger of Allah, you swore that you would not give me a mount.’ He said, ‘And [now] I swear that I will give you a mount.'”
(Musnad Ahmad, Vol. 3, p . 108. The isnaad of this hadeeth is Saheeh. according to the conditions set by al-Bukhaaree and Muslim.)
Note:
A mount is a means of conveyance, such as a horse or a camel, on which to ride.
In the Muslim’s version, the Prophet (PBUH) said to him, ” It was not I who provided you with a mount, but Allah has provided you with that. So far as I am concerned, by Allah, if He so wills, I would not swear, but if, later on, I would see better than it, I would break the vow and expiate for it and do that which is better.”
Source:
Thulaathiyyaat Musnad Ahmad ibn Hanbal (may Allah have mercy on him)
Reports of Imaam Ahmad that have only three narrators between him and the Prophet, peace, and blessings be upon him.
Shaykh Muhammad ibn Ahmad ibn Saalim as–Saffaareenee al–Hanbalee ~(1114 –1188 AH)