'Hair of His Head' in the Bible

All the days of the vow of his separation there shall no razor come upon his head: until the days shall be fulfilled, in which he separateth himself to the LORD, he shall be holy, and shall let the locks of the hair of his head grow.

However the hair of his head began to grow again after he was shaved.

And the people said to Saul, Shall Jonathan die, who hath wrought this great salvation in Israel? By no means: as the LORD liveth, there shall not one hair of his head fall to the ground; for he hath wrought with God this day. So the people rescued Jonathan, that he died not.

And when he polled his head, (for it was at every year's end that he polled it: because the hair was heavy on him, therefore he polled it:) he weighed the hair of his head at two hundred shekels after the king's weight.

I beheld till the thrones were cast down, and the Ancient of days did sit, whose garment was white as snow, and the hair of his head like the pure wool: his throne was like the fiery flame, and his wheels as burning fire.