Deuteronomy 16:9-12

MLV(i) 9 You will number to you seven weeks. From the time you begin to put the sickle to the standing grain you will begin to number seven weeks. 10 And you will keep the feast of weeks to Jehovah your God with a tribute of a free-will offering from your hand, which you will give, just-as Jehovah your God graces you.
11 And you will rejoice before Jehovah your God, you and your son and your daughter and your man-servant and your maid-servant and the Levite who is within your gates and the traveler and the fatherless and the widow, who are in the midst of you, in the place which Jehovah your God will choose to cause his name to dwell there, 12 and you will remember that you were a bondman in Egypt. And you will observe and do these statutes.