"If, when reaping your harvest, you forget to bring in a sheaf from the field, don't go back after it. Leave it for the migrants, orphans, and widows; then the Lord your God will bless and prosper all you do. When you beat the olives from your olive trees, don't go over the boughs twice; leave anything remaining for the migrants, orphans, and widows. It is the same for the grapes in your vineyard; don't glean the vines after they are picked, but leave what's left for those in need. Remember that you were slaves in the land of Egypt - that is why I am giving you this command." Deuteronomy 25:19-22

I think we are conditioned to always try to get the most out of everything, not doing so is sometimes seen as lazy, foolish, incompetent even. Yet must charity always be outright?