In 15:19-23 we see that the children of Israel were to worship God also by offering the firstborn males of the herd and of the flock.
"All firstborn males that are brought forth in your herd and flock you shall sanctify to Jehovah your God; you shall not do work with your firstborn ox, nor shall you shear your firstborn sheep" (v. 19). Here we see that the children of Israel could not use for their own purpose the firstborn of the herd and of the flock, which were to be sanctified to God. Because the firstborn of the ox belonged to God, it could not be used for work. Likewise, because the firstborn of the sheep belonged to God, it could not be shorn. The people had no right to use what had been sanctified to God.
"You and your household shall eat it before Jehovah your God year by year in the place which Jehovah will choose" (v. 20). The firstborn, like the tithes, were to be eaten, but only in the place which Jehovah God would choose.
Any animal having a blemish, lameness, or blindness was not to be sacrificed to Jehovah God (v. 21), for that was an abomination to Him (17:1). Such animals could be eaten, except for the blood, in the place where the people lived (15:22-23). From this we see that a certain portion was to be given to God in the place of His choice and enjoyed there with Him; however, other portions, having nothing to do with the worship of God, could be enjoyed by the people where they lived.
According to 16:1-17, the children of Israel were to worship God by keeping the three main annual festivals: the Feast of Unleavened Bread (the Feast of Passover), the Feast of Weeks (the Feast of Pentecost), and the Feast of Tabernacles. These festivals respectively signify the feasts of the redemption of Christ, the producing of the church, and the coming kingdom. (For the details, please see the life-study on Leviticus 23.)