Numbers 19:9 explains the origin of the water of purification needed here — the ashes of the red heifer.

Numbers 19:18 gives the method of sprinkling the water for impurity, which is required to avoid being cut off as stated here.

Numbers 19:20 repeats almost verbatim the same law about uncleanness and being cut off for not using purification water.

Numbers 15:30 also uses the phrase 'cut off' for defiant sin, paralleling the penalty here for failing to purify.

Numbers 9:13 also uses 'cut off' for failing to observe Passover — same penalty for neglecting a command.

Leviticus 7:20 imposes the same 'cut off' penalty for uncleanness when eating sacred offerings — both enforce holiness.

Leviticus 15:31 similarly warns that uncleanness defiles the tabernacle and brings death — directly reinforcing this principle.

Leviticus 22:3 also decrees being 'cut off' for approaching holy things while unclean — same consequence for defilement.

Hebrews 10:29 builds on the OT penalty (like being cut off here) to argue that rejecting Christ deserves even harsher punishment.

2 Chronicles 30:19 alludes to this law, granting mercy for those who ate the Passover without proper cleanness.

Ezekiel 36:25 uses the imagery of sprinkling clean water to promise spiritual cleansing — a typological fulfillment of the purification ritual.

Leviticus 5:3 addresses uncleanness from touching a corpse, requiring a guilt offering when hidden—complementary to the water purification here.