This is the first mention of the three great Yearly Festivals. The feast of Unleavened bread, in its connection with the Paschal Lamb, is spoken of in Exo. 12; 13: but the two others are here first named. The whole three are spoken of as if they were familiarly known to the people. The points that are especially enjoined are that every male Israelite should attend them at the sanctuary (compare Exo 34:23), and that he should take with him an offering for Yahweh, presenting himself before his King with his tribute in his hand. That this condition belonged to all the feasts, though it is here stated only in regard to the Passover, cannot be doubted. See Deu 16:16.
Exo 23:15-16
On the Feast of Unleavened Bread, or the Passover, see Exo. 12:1-20, Exo 12:43-50; Exo 13:3-16; Exo 34:18-20; Lev 23:4-14. On the Feast of the Firstfruits of Harvest, called also the Feast of Weeks, and the Feast of Pentecost, see Exo 34:22; Lev 23:15-21. On the Feast of Ingathering, called also the Feast of Tabernacles, see Lev 23:34-36, Lev 23:39-43.
Exo 23:16
In the end of the year - Compare Exo 34:22. The year here spoken of must have been the civil or agrarian year, which began after harvest, when the ground was prepared for sowing. Compare Lev 23:39; Deu 16:13-15. The sacred year began in spring, with the month Abib, or Nisan. See Exo 12:2 note, and Lev 25:9.
When thou hast gathered - Rather, when thou gatherest in.