Narrated Abu Hurairah: A man asked the Messenger of Allah (ﷺ): Messenger of Allah, which sadaqah (charity) is the best ? He replied: (The best sadaqah is) that you give something as sadaqah (charity) when you are healthy, greedy, expect survival and fear poverty, and not that you postpone it until your death. and then you say: For so-and-so is such-and-such, and for so-and-so is such-and-such, while it was already for so-and-so.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا عَبْدُ الْوَاحِدِ بْنُ زِيَادٍ، حَدَّثَنَا عُمَارَةُ بْنُ الْقَعْقَاعِ، عَنْ أَبِي زُرْعَةَ بْنِ عَمْرِو بْنِ جَرِيرٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَجُلٌ لِلنَّبِيِّ صلى الله عليه وسلم يَا رَسُولَ اللَّهِ أَىُّ الصَّدَقَةِ أَفْضَلُ قَالَ " أَنْ تَصَدَّقَ وَأَنْتَ صَحِيحٌ حَرِيصٌ تَأْمُلُ الْبَقَاءَ وَتَخْشَى الْفَقْرَ وَلاَ تُمْهِلْ حَتَّى إِذَا بَلَغَتِ الْحُلْقُومَ قُلْتَ لِفُلاَنٍ كَذَا وَلِفُلاَنٍ كَذَا وَقَدْ كَانَ لِفُلاَنٍ " .
sunnah.com