Leviticus 23:38 - Matthew Poole's English Annotations on the Holy Bible

Beside the sabbaths, i.e. the offerings of the weekly sabbaths, by a metonymy, as the day is sometimes put for the actions done in it, as Proverbs 27:1 1 Corinthians 3:13. God will not have any sabbath sacrifice diminished, because of the addition of others proper to any, other feast. And it is here to be noted, that though other festival days are sometimes called sabbaths, as here Leviticus 23:39, yet these are here called the sabbaths of the Lord, in way of contradistinction to other days of rest, to show that this was more eminently such than other feast-days, which also sufficiently appears from the fourth commandment. Beside your gifts, which, being here distinguished from free-will offerings made to the Lord, may seem to note what they freely gave to the priests over and above their first-fruits and tithes, or other things which they were enjoined to give.