'Clean' in the Bible

I went on looking till the seats of kings were placed, and one like a very old man took his seat: his clothing was white as snow, and the hair of his head was like clean wool; his seat was flames of fire and its wheels burning fire.

And he said to him, For two thousand, three hundred evenings and mornings; then the holy place will be made clean.

And some of those who are wise will have wisdom in testing themselves and making themselves clean, till the time of the end: for it is still for the fixed time.

Till a number are tested and make themselves clean; and the evil-doers will do evil; for not one of the evil-doers will have knowledge; but all will be made clear to those who are wise.