19:2 a red heifer The cow must have reddish hair to be acceptable for the ritual. Since red yarn is also added to the fire, the color may be specified due to its symbolic association with blood.

on which a yoke has not been placed Describes a heifer that has never been used for a non-sacred purpose. Compare Deut 21:1–9; 1 Sam 6:7.

19:3 Eleazar the priest It is unclear why this duty was not given to Aaron, the high priest, but it was likely related to keeping Aaron from becoming ritually impure. Eleazar was in charge of the transportation of the tabernacle during the wilderness march (Num 3:32; 4:16).

will be brought out to a place outside the camp The animal is burned up outside the camp, similar to the purification (or sin) offering (Lev 4:12). However, the heifer in this case is also slaughtered outside the camp, not at the sacrificial altar.

19:4 blood The essential ingredient for purification, blood was considered a sort of detergent that removed impurity.

spatter it The ritual sprinkling of blood seven times toward the tent of meeting is comparable to the sevenfold sprinkling of blood required for the purification (or sin) offering (Lev 4:6; 16:14).

19:6 cedar wood, hyssop, and crimson thread The same ingredients are used in other purification rituals (e.g., Lev 14:4, 51–52).

19:7 will be unclean The people involved in the ritual are rendered unclean, but their ritual purity is restored after they wash their clothes, bathe, and wait until evening (compare Lev 11:25).

19:9 in a clean place outside the camp The ashes of the red heifer must be kept free of contamination.

waters of impurity The ashes were intended for use in this water mixture. See note on Num 19:1–22.

a purification offering This designation connects the red heifer ritual with the chatta’th (the purification or sin offering) and indicates its purpose of providing purification. See note on Lev 4:1–5:13.

19:10 one who dwells as an alien in their midst Refers to resident aliens. Everyone living in the promised land must purify themselves to prevent contamination of the sanctuary and its sacred space (Num 19:13); contamination can be spread within the community (vv. 13, 20; compare 31:19).

19:11 for seven days The seven-day length of time is common for purification procedures (e.g., Lev 12:2; 14:9; 15:13). A purification offering was required on the eighth day or later depending on the contaminating circumstances (Lev 12:1–8; 14:10, 21–23; 15:14–15, 28–29). To be purified by contamination from a corpse, washing with the ashes mixed with water on the third and seventh days is substituted for the offering.

19:14 all who are in the tent Ancient Israelites conceived of impurity as a physical substance that could be contained (e.g., inside the tent) or spread. They thought it could invade objects (e.g., the vessels in Num 19:15), or move from one person or object to another (e.g., the grave of the dead in v. 16).

19:17 the powder of the burnt purification offering Refers to the ashes from the offered red heifer (vv. 1–10).

19:19 clean person Refers to the one handling the ashes mixed with water.