Gather yourselves - to my sacrifice - This is an allusion to a custom common in the east: when a sacrifice is made, the friends and neighbors of the party sacrificing are invited to come and feast on the sacrifice.
The purposes of the past dispensation shall be made clear to God‘s people themselves and to the pagan. His judgments were the consequence of their sins; and these sins once abandoned, the favor of their God will return in yet more abundance.
Compare Acts 2:17. Peter distinctly appropriates these prophecies (marginal references) to the outpouring of the Holy Spirit on the day of Pentecost, and the inauguration of the Church of Christ by that miraculous event. This was the beginning of the fulfillment. They shall find their consummation when time shall be no more.