Sahih Bukhari Volume 2, Book 24, Hadith 1420

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا عَبْدُ الْوَاحِدِ، حَدَّثَنَا عُمَارَةُ بْنُ الْقَعْقَاعِ، حَدَّثَنَا أَبُو زُرْعَةَ، حَدَّثَنَا أَبُو هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ جَاءَ رَجُلٌ إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَ يَا رَسُولَ اللَّهِ أَىُّ الصَّدَقَةِ أَعْظَمُ أَجْرًا قَالَ ‏"‏ أَنْ تَصَدَّقَ وَأَنْتَ صَحِيحٌ شَحِيحٌ، تَخْشَى الْفَقْرَ وَتَأْمُلُ الْغِنَى، وَلاَ تُمْهِلُ حَتَّى إِذَا بَلَغَتِ الْحُلْقُومَ قُلْتَ لِفُلاَنٍ كَذَا، وَلِفُلاَنٍ كَذَا، وَقَدْ كَانَ لِفُلاَنٍ ‏"

Narrated By Abu Huraira : A man came to the Prophet and asked, "O Allah's Apostle! Which charity is the most superior in reward?" He replied, "The charity which you practice while you are healthy, niggardly and afraid of poverty and wish to become wealthy. Do not delay it to the time of approaching death and then say, 'Give so much to such and such, and so much to such and such.' And it has already belonged to such and such (as it is too late)."