John Gill Commentary Deuteronomy 16:14

"and thou shalt rejoice in thy feast, thou, and thy son, and thy daughter, and thy man-servant, and thy maid-servant, and the Levite, and the sojourner, and the fatherless, and the widow, that are within thy gates." — Deuteronomy 16:14 (ASV)

And you shall rejoice in your feast
At this feast of tabernacles and ingathering of the fruits of the earth, in token of gratitude and thankfulness for the goodness of God bestowed on them; the Targum of Jonathan adds, with the flute and the pipe, making use of instrumental music to increase the joy on this occasion:

you and your son (See Gill on Deuteronomy 16:11)