Umar bin Khattab reported,

I gave a horse as a charitable contribution for the cause of Allah, but the man who received it neglected it, or sold it. I wanted to buy it back, thinking he would sell it at a low price, so I asked the Prophet ﷺ about it.He said, "Do not buy it, even for a single dirham, for the one who takes back what he has given is like a dog that returns to its vomit."

Bukhari 3003

Sahih

حدثنا إسماعيل حدثني مالك عن زيد بن أسلم عن أبيه قال سمعت

عمر بن الخطاب رضي الله عنه يقول

حملت على فرس في سبيل الله فابتاعه أو فأضاعه الذي كان عنده فأردت أن أشتريه وظننت أنه بائعه برخص فسألت النبي ﷺ فقال لا تشتره وإن بدرهم فإن العائد في هبته كالكلب يعود في قيئه

البخاري 3003صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Jihad and expeditions
Chapter
If one gave a horse in charity and then saw it being sold
Numbering
Darussalam 3003
Bukhari 3003