And thou shalt observe the feast of weeks,.... The feast of Pentecost, called the feast of weeks, because seven sabbaths or weeks, or fifty days, were to be reckoned from the day in the passover feast, on which the sheaf of the wave offering was brought, Lev 23:15 and which was also called the feast of the first fruits of wheat harvest, to distinguish it from the barley harvest, at the time of the passover, when a sheaf of barley was the wave offering to the Lord; but at this two loaves or cakes of fine wheaten flour were brought as the first fruits of the wheat harvest, see Lev 23:17. and the feast of ingathering at the year's end; which was the feast of tabernacles, called the feast of ingathering, because at this time all the fruits of the earth, the corn, wine, and oil, and all others were gathered in; and this was at the close of the old year, and at the beginning of the new, according to the ancient account, which made Tisri or September the first month in the year; See Gill on Exo 23:16.