"He who gives his wealth to purify himself," meaning: seeking nearness to his Lord through it. The interpretation of al-Hasan is that this refers to voluntary charity.
﴿الَّذِي يُؤْتِي مَاله يتزكى﴾ يَتَقَرَّبُ بِهِ إِلَى رَبِّهِ؛ تَفْسِيرُ الْحسن: إِن هَذَا تطوع
