I heard ʿUmar bin Al-Khattab saying, "I gave a horse to be ridden in Allah's Cause and the person who got it intended to sell it or neglected it. So, I wanted to buy it as I thought he would sell it cheap. I consulted the Prophet ﷺ who said, "Do not buy it even if for one Dirham, because he who takes back his gift is like a dog swallowing its vomit."  

أَنَّهُ بَائِعُهُ بِرُخْصٍ فَسَأَلْتُ النَّبِيَّ ﷺ فَقَالَ لاَ تَشْتَرِهِ وَإِنْ بِدِرْهَمٍ فَإِنَّ الْعَائِدَ فِي هِبَتِهِ كَالْكَلْبِ يَعُودُ فِي قَيْئِهِ  

I gave a horse in Allah's Cause. The person to whom it was given, did not look after it. I intended to buy it from him, thinking that he would sell it cheap. When I asked the Prophet ﷺ he said, "Don't buy it, even if he gives it to you for one Dirham, as the person who takes back what he has given in charity, is like a dog that swallows back its vomit." (Using translation from Bukhārī 2623)  

عَنْ ذَلِكَ رَسُولَ اللَّهِ ﷺ فَقَالَ «لَا تَبْتَعْهُ وَإِنْ أَعْطَاكَهُ بِدِرْهَمٍ وَاحِدٍ فَإِنَّ الْعَائِدَ فِي صَدَقَتِهِ كَالْكَلْبِ يَعُودُ فِي قَيْئِهِ»  

[Machine] "Regarding this, the Messenger of Allah ﷺ said, 'Do not buy it, even if he gives it to you for one dirham, for the return on his charity is like a dog that returns to its vomit.'"  

عَنْ ذَلِكَ رَسُولَ اللهِ ﷺ فَقَالَ لَا تَشْتَرِهِ وَإِنْ أَعْطَاكَ بِدِرْهَمٍ وَاحِدٍ فَإِنَّ الْعَائِدَ فِي صَدَقَتِهِ كَالْكَلْبِ يَعُودُ فِي قَيْئِهِ