﴿ لَن تَنَالُوا۟ ٱلْبِرَّ حَتَّىٰ تُنفِقُوا۟ مِمَّا تُحِبُّونَ ۚ وَمَا تُنفِقُوا۟ مِن شَىْءٍۢ فَإِنَّ ٱللَّهَ بِهِۦ عَلِيمٌۭ ﴾

“[But as for you, O believers,] never shall you attain to true piety unless you spend on others out of what you cherish yourselves; and whatever you spend - verily, God has full knowledge thereof.”

You will not attain piety: any act that brings a person closer to God is piety (birr). The only way to become closer to Him is to absolve oneself (tabarrī) of all that is other than Him. Thus when one loves something he becomes veiled thereby from God, exalted be He, and is guilty of a subtle associationism (shirk) because his love is attached to something other than God, as God says Yet there be people who take to themselves compeers besides God, loving them as God is loved [Q. 2:165], preferring that their souls love these over God. Such a person has become distant from God on three accounts: the love of other than the Truth; association of others [with God]; and preferring one's soul over the Truth. But is such a person were to prefer God over his soul and voluntarily give away that [love of others to God], expending it [for God], then that distance would disappear and nearness would ensue. Otherwise, he will remain veiled, even if he were to expend many times over of something else, and will not attain piety because God knows what is being expended and [knows of] his being veiled by something other than Him.