Numbers 6:18

And the Nazarite shall shave the head of his separation at the door of the tabernacle of the congregation, and shall take the hair of the head of his separation, and put it in the fire which is under the sacrifice of the peace offerings.

Cross-reference

Numbers 6:5 commands no razor on the head during the vow — here in verse 18 the Nazirite shaves at completion, fulfilling that rule.

Numbers 6:9 provides the rule for shaving after defilement, distinct from the completion shave here.

In Acts 18:18, Paul shaves his head at Cenchreae, directly practicing the Nazirite vow completion described here.

Acts 21:24 mentions shaving heads as part of a Nazirite vow purification, echoing the same practice.