Leviticus 15:17
And every garment, and every skin, whereon is the seed of copulation, shall be washed with water, and be unclean until the even. And every garment, and every skin, whereon is the seed of copulation, shall be washed with water, and be unclean until the even.
Leviticus 15-17 stands within Leviticus 5-23, which deals largely with laws relating to sacrifices and offerings, the consecration and duties of the priests, and the various feasts of the year. Every garment and every skin marked by seminal discharge was to be washed with water, made visibly clean, and remain unclean until the evening. Being unclean until the evening, in the sanitation rules of Leviticus 15, meant staying apart from others for the rest of the day, allowing air and sunshine to complete disinfection. This outward washing of an object made physically unclean prepared for the sanctuary's deeper cleansing by blood from moral defilement.
Like the rest of Leviticus, it emphasizes the exceeding sinfulness of sin through a mighty object-lesson from God. Each detail of these laws had its meaning and finds fuller meaning in the sacrifice, life, and work of Jesus Christ, receiving new life and blessing when he is seen in them as the Lamb of God that takes away the sin of the world. As part of the cleansing laws given to ancient Israel, it serves as an example for the remnant, warning against turning away from cleansing and health reform, with the lesson to prepare clean vessels for the reception of the latter rain.