Charles Ellicott Commentary Leviticus 23:15

"And ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave-offering; seven sabbaths shall there be complete:" — Leviticus 23:15 (ASV)

You shall count ... from the day after the sabbath. —That is, from the day following the first day of holy convocation, which was a rest day. As this was the fifteenth of Nisan, the counting began from the sixteenth , the day on which the omer of the first-fruits was presented to the Lord.

Seven sabbaths shall be complete. —Better, seven weeks shall be complete. That is, seven entire weeks, making forty-nine days. The expression "sabbath" denotes here a week; hence, the parallel passage substitutes the word "week," namely, seven weeks shall you number to you (Deuteronomy 16:9). The same usage is to be found in the New Testament.

Thus, the passage rendered in the Authorized Version, the first day of the week, is the first day of the sabbath (Matthew 28:1); and I fast twice in the week (Luke 18:12) is I fast twice in the sabbath.

In accordance with the injunction given here, the Jews to this day begin to count the forty-nine days at the conclusion of the evening service on the second day of Passover, and pronounce the following blessing every evening of the forty-nine days: “Blessed are you, O Lord our God, King of the universe, who have sanctified us with your commandments, and have enjoined us to count the omer. This is the first day of the omer. May it please you, O Lord our God, and the God of our fathers, to rebuild the sanctuary speedily in our days, and give us our portion in your Law.”