Mishnah — Seder Moed, Tractate PesachimChapter 1…
“ This refers to an individual who had the status of primary uncleanness, and then immersed in a ritual bath. His uncleanness is not entirely removed until the sun sets that day. This is derived from the verse: "The sun shall come in, and he shall be clean; afterward he may eat of the holies, for that is his food." (Leviticus 22:7) . Any priestly gifts that he touches during this time acquire tertiary uncleanness. ”
