Sahih Bukhari Volume 9, Book 93, Hadith 7166

وَعَنِ الزُّهْرِيِّ، قَالَ حَدَّثَنِي سَالِمُ بْنُ عَبْدِ اللَّهِ، أَنْ عَبْدَ اللَّهِ بْنَ عُمَرَ، قَالَ سَمِعْتُ عُمَرَ، يَقُولُ كَانَ النَّبِيُّ صلى الله عليه وسلم يُعْطِينِي الْعَطَاءَ فَأَقُولُ أَعْطِهِ أَفْقَرَ إِلَيْهِ مِنِّي‏.‏ حَتَّى أَعْطَانِي مَرَّةً مَالاً فَقُلْتُ أَعْطِهِ مَنْ هُوَ أَفْقَرُ إِلَيْهِ مِنِّي‏.‏ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ خُذْهُ فَتَمَوَّلْهُ وَتَصَدَّقْ بِهِ، فَمَا جَاءَكَ مِنْ هَذَا الْمَالِ وَأَنْتَ غَيْرُ مُشْرِفٍ وَلاَ سَائِلٍ فَخُذْهُ، وَمَا لاَ فَلاَ تُتْبِعْهُ نَفْسَكَ ‏"

Narrated 'Abdullah bin 'Umar: I have heard 'Umar saying, "The Prophet used to give me some money (grant) and I would say (to him), 'Give it to a more needy one than me.' Once he gave me some money and I said, 'Give it to a more needy one than me.' The Prophet said (to me), 'Take it and keep it in your possession and then give it in charity. Take whatever comes to you of this money while you are not keen to have it and not asking for it; take it, but you should not seek to have what you are not given.'"