Sahih al-Bukhari 2636

Arabic

حَدَّثَنَا الْحُمَيْدِيُّ، أَخْبَرَنَا سُفْيَانُ، قَالَ سَمِعْتُ مَالِكًا، يَسْأَلُ زَيْدَ بْنَ أَسْلَمَ قَالَ سَمِعْتُ أَبِي يَقُولُ، قَالَ عُمَرُ ـ رضى الله عنه ـ حَمَلْتُ عَلَى فَرَسٍ فِي سَبِيلِ اللَّهِ، فَرَأَيْتُهُ يُبَاعُ، فَسَأَلْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم فَقَالَ ‏ "‏ لاَ تَشْتَرِ، وَلاَ تَعُدْ فِي صَدَقَتِكَ ‏"‏‏.‏

English translation

Narrated `Umar bin Al-Khattab:Once I gave a horse (for riding) in Allah's Cause. Later I saw it being sold. I asked Allah's Messenger (ﷺ) (whether I could buy it). He said, "Don't buy it, for you should not get back what you have given in charity

Reference: Sahih al-Bukhari 2636, Book of Gifts. English translation by Dr. Muhammad Muhsin Khan.