"I heard 'Umar say: 'I gave a horse to someone to ride in the cause of Allah, the Mighty and Sublime, and the one who kept it neglected it. I wanted to buy it back from him, and I thought that he would sell it at a cheap price. I asked the Messenger for Allah about that and he said: Do not buy it, even if he gives it to you for a Dirham. The one who takes back his charity is like the dog that goes back to its own vomit. "' (Using translation from Nasāʾī 2615)  

سَمِعْتُ عُمَرَ يَقُولُ حَمَلْتُ عَلَى فَرَسٍ فِي سَبِيلِ اللهِ فَأَضَاعَهُ الَّذِي كَانَ عِنْدَهُ فَأَرَدْتُ أَنْ أَبْتَاعَهُ مِنْهُ وَظَنَنْتُ أَنَّهُ بَائِعُهُ بِرُخْصٍ فَسَأَلْتُ عَنْ ذَلِكَ رَسُولَ اللهِ ﷺ فَقَالَ «لَا تَشْتَرِهِ وَإِنْ أَعْطَاكَهُ بِدِرْهَمٍ فَإِنَّ الْعَائِدَ فِي صَدَقَتِهِ كَالْكَلْبِ يَعُودُ فِي قَيْئِهِ»  

he gave someone a horse to ride in the cause of Allah, then he saw it offered for sale and wanted to buy it. The Prophet said to him: "Do not think of buying back what you have given in charity." (Using translation from Nasāʾī 2616)  

أَنَّهُ حَمَلَ عَلَى فَرَسٍ فِي سَبِيلِ اللهِ فَرَآهَا تُبَاعُ فَأَرَادَ شِرَاءَهَا فَقَالَ لَهُ النَّبِيُّ ﷺ «لَا تَعْرِضْ فِي صَدَقَتِكَ»  

[Machine] He buys it, then he goes to the Messenger of Allah ﷺ and consults him in that. The Messenger of Allah ﷺ tells him, "Do not count it as a charity."  

أَنْ يَشْتَرِيَهُ ثُمَّ أَتَى رَسُولَ اللهِ ﷺ فَاسْتَأْمَرَهُ فِي ذَلِكَ فَقَالَ لَهُ رَسُولُ اللهِ ﷺ «لَا تَعُدْ فِي صَدَقَتِكَ»