Sayyiduna Abu Mas’ud Badri (may Allah be pleased with him) narrates: We used to carry loads, then when someone would bring something to give in charity, it would be said: He has done this for show. If someone brought half a sa’, it would be said: Allah is independent of this. So regarding this, the verse was revealed: "Those who criticize the believers concerning the charities they give."
Hadith Referenceصحیح ابن حبان / كتاب الزكاة / 3376
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم