Numbers 6:9
And if any man die very suddenly by him, and he hath defiled the head of his consecration; then he shall shave his head in the day of his cleansing, on the seventh day shall he shave it. And if any man die very suddenly by him, and he hath defiled the head of his consecration; then he shall shave his head in the day of his cleansing, on the seventh day shall he shave it.
The rule forms part of the instructions governing the Nazarite vow. When a death occurred very suddenly beside the consecrated person, that proximity defiled the head of his consecration. He was then required to shave his head on the seventh day of his cleansing, as part of the purification period and the offerings required for completing the vow.