Hadithcore
Mishkat al-Masabih, 1888

Abu Huraira reported God’s messenger as saying, “If anyone gives as <i>sadaqa</i> the equivalent of a date from something lawfully earned, for God accepts only what is lawful, God will accept it with His right hand, then foster it for the one who gave it as one of you fosters his colt, till it becomes like a mountain.” (Bukhari and Muslim.)

وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ تَصَدَّقَ بِعَدْلِ تَمْرَةٍ مِنْ كَسْبٍ طَيِّبٍ وَلَا يَقْبَلُ اللَّهُ إِلَّا الطَّيِّبَ فَإِنَّ اللَّهَ يَتَقَبَّلُهَا بِيَمِينِهِ ثُمَّ يُرَبِّيهَا لِصَاحِبِهَا كَمَا يُرَبِّي أَحَدُكُمْ فَلُوَّهُ حَتَّى تَكُونَ مِثْلَ الْجَبَل»

References1 variant
In-Book Reference
Book 6, Hadith 115