Yahya related to me from Zayd ibn Aslam that his father said that he had heard Umar ibn al-Khattab say, "I once gave a noble horse to carry somebody in the way of Allah, and the man neglected it. I wished to buy it back from him and I thought that he would sell it cheaply. I asked the Messenger of Allah ﷺ about it and he said, 'Do not buy it, even if he gives it to you for one dirham, for someone who takes back his sadaqa is like a dog swallowing its own vomit.' "

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ زَيْدِ بْنِ أَسْلَمَ، عَنْ أَبِيهِ، أَنَّهُ قَالَ سَمِعْتُ عُمَرَ بْنَ الْخَطَّابِ، وَهُوَ يَقُولُ حَمَلْتُ عَلَى فَرَسٍ عَتِيقٍ فِي سَبِيلِ اللَّهِ - وَكَانَ الرَّجُلُ الَّذِي هُوَ عِنْدَهُ قَدْ أَضَاعَهُ - فَأَرَدْتُ أَنْ أَشْتَرِيَهُ مِنْهُ وَظَنَنْتُ أَنَّهُ بَائِعُهُ بِرُخْصٍ فَسَأَلْتُ عَنْ ذَلِكَ رَسُولَ اللَّهِ ﷺ فَقَالَ " لاَ تَشْتَرِهِ وَإِنْ أَعْطَاكَهُ بِدِرْهَمٍ وَاحِدٍ فَإِنَّ الْعَائِدَ فِي صَدَقَتِهِ كَالْكَلْبِ يَعُودُ فِي قَيْئِهِ " .