The 'fellowship' or 'peace' offering — one of the main sacrifice types, associated with communal eating and celebration before God. Unlike burnt offerings (wholly consumed), the shelem was shared.
The peace offering created shalom — wholeness and right relationship — between God and worshipper. The shared meal at the altar foreshadowed communion and the Messianic banquet.
Amos 5:22 shows the danger of ritual without justice — God rejects shelem from those who oppress the poor. Ritual and ethics cannot be separated. Christ is the true peace offering who achieves real shalom.