Messenger of Allah ﷺ said, "If one give in charity what equals one date-fruit from the honestly earned money and Allah accepts only the honestly earned money --Allah takes it in His right (hand) and then enlarges its reward for that person (who has given it), as anyone of you brings up his baby horse, so much s that it becomes as big as a mountain
قَالَ رَسُولُ اللَّهِ ﷺ مَنْ تَصَدَّقَ بِعَدْلِ تَمْرَةٍ مِنْ كَسْبٍ طَيِّبٍ وَلاَ يَقْبَلُ اللَّهُ إِلاَّ الطَّيِّبَ وَإِنَّ اللَّهَ يَتَقَبَّلُهَا بِيَمِينِهِ ثُمَّ يُرَبِّيهَا لِصَاحِبِهِ كَمَا يُرَبِّي أَحَدُكُمْ فَلُوَّهُ حَتَّى تَكُونَ مِثْلَ الْجَبَلِ