He shall purify: Yithchatta:, literally, "he shall sin himself," i.e., not add sin, but take it away, purify. So we say to fleece, and to skin, which do not signify to add a fleece, or a skin, but to take one away. Numbers 19:17-18; Psalms 51:7; Ezekiel 36:25; Acts 15:9; Revelation 7:14
third day: Numbers 31:19; Exodus 19:11, Exodus 19:15; Leviticus 7:17; Hosea 6:2; 1 Corinthians 15:3-4