Numbers 19:20
But the man that shall be unclean, and shall not purify himself, that soul shall be cut off from among the congregation, because he hath defiled the sanctuary of the Lord: the water of separation hath not been sprinkled upon him; he is unclean.
Cross-reference
Numbers 19:13 states the same consequence for failing to purify from corpse contact — being cut off for defiling the sanctuary.
Numbers 19:9 describes the preparation of the water of purification — the very water that must be sprinkled on the unclean person in verse 20.
Numbers 15:30 decrees cutting off for defiant sin — similar to the penalty here for willful refusal to purify after corpse contact.
Leviticus 15:31 similarly warns of death for defiling the tabernacle through uncleanness, reinforcing the same consequence as Numbers 19:20.
Leviticus 20:3 also describes being cut off for defiling the sanctuary, directly paralleling the penalty in Numbers 19:20 for uncleanness.
Ezekiel 14:8 uses the same 'cut off from among My people' phrasing for idolaters — a parallel judgment for defilement.
1 Corinthians 3:17 warns that defiling God's temple brings destruction — parallel to defiling the sanctuary here.
Genesis 17:14 imposes cutting off for neglecting circumcision — analogous to the cutting off here for neglecting purification.
Leviticus 17:16 states that not washing after uncleanness brings bearing iniquity, a parallel consequence to being cut off for not cleansing in Numbers 19:20.
2 Chronicles 30:18 shows a case where uncleanness was overlooked by royal intercession — a contrast to the strict 'cut off' penalty here.