leaven
The use of leaven here is significant. Peace with God is something which the believer shares with God. Christ is our peace-offering (Ephesians 2:13). Any thanksgiving for peace must, first of all, present Him. In verse 12 (Leviticus 7:12), we have this, in type, and so leaven is excluded. In verse 13 (Leviticus 7:13), it is the offerer who gives thanks for his participation in the peace, and so leaven fitly signifies, that though having peace with God through the work of another, there is still evil in him. This is illustrated in (Amos 4:5) where the evil in Israel is before God.