Deuteronomy 24:18-22

18but you shall remember that you were a slave in Egypt and the Lord your God redeemed you from there; therefore I command you to do this.

19"When you reap your harvest in your field and forget a sheaf in the field, you shall not go back to get it. It shall be for the sojourner, the fatherless, and the widow, that the Lord your God may bless you in all the work of your hands.

20When you beat your olive trees, you shall not go over them again. It shall be for the sojourner, the fatherless, and the widow.

21When you gather the grapes of your vineyard, you shall not strip it afterward. It shall be for the sojourner, the fatherless, and the widow.

22You shall remember that you were a slave in the land of Egypt; therefore I command you to do this.