'Reaping' in the Bible

"When you are reaping in the field, and you overlook a sheaf, don't return to get it. Let it remain for the foreigner, the orphan, or the widow, in order that the LORD your God may bless everything you undertake.

it will be as if harvesters gather standing grain, reaping the ears by hand, or it will be as if grain is harvested in the valley of Rephaim.