Deuteronomy 27:7

Peace offerings — i.e., offerings for health, salvation, or deliverance already granted. On this occasion, the passage of Jordan, and the arrival of Israel in the heart of the country, would be good ground for thanksgiving before God.

And shalt eat there, and rejoice.-The peace offerings were the only kind of which the worshipper and his family might partake. They were, therefore, the natural accompaniment of rejoicing and thanksgiving.