Surah 2. Al-Baqara, Ayah 265

 It could also mean “… seeking Allah’s pleasure and proving their sincerity.”

True charity is like a field with good soil on a high situation. It catches good showers of rain, the moisture penetrates the soil, and yet its elevated situation keeps it well-drained, and healthy favorable conditions increase its output enormously. But supposing even that the rain is not abundant, it catches dew and makes the most of any little moisture it can get, and that is sufficient for it. So a man of true charity is spiritually helathy; he is best suited to attract the bounties of God, which he does not hoard selfishly but circulates freely. In lean times he still produces good works, and is content with what he has. He looks to God's pleasure and the strengthening of his own soul.