Sacrifices for sin in the Old Testament tabernacle left a residue of ashes (and undoubtedly bits of wood and bone and meat not totally consumed by the fire). With the use of bowls (also translated as “basins”), the Levites had to carry this residue out of the tabernacle to a place outside the camp for total incineration (Exodus 27:3; Leviticus 4:12; Leviticus 6:11). Inasmuch as the ashes were residue of lamb-become-sin, these ashes represented the (remaining) wrath of God.
1 Then I heard a loud voice from the temple telling the seven angels, “Go and pour out on the earth the seven bowls of the wrath of God.”