I went along with some men from the Ash-ariyin to Allah's Messenger (ﷺ) and it happened that I met him
while he was in an angry mood. We asked him to provide us with mounts, but he swore that he would
not give us any. Later on he said, "By Allah, Allah willing, if ever I take an oath (to do something)
and later on I find something else better than the first, then I do the better one and give expiation for
the dissolution of my oath."
Sahih al-Bukhari Book 83, Hadith 57