Deuteronomy 24:20

When thou beatest thine olive tree
With sticks and staves, to get off the olives when ripe:

thou shall not go over the boughs again;
to beat off some few that may remain; they were not nicely to examine the boughs over again, whether there were any left or not:

it shall be for the stranger, for the fatherless, and for the widow;
who might come into their oliveyards after the trees had been beaten, and gather what were left.