Another matter, “A man, if he will have on the skin of his flesh” – that is what is written: “Who cleaved a channel for the torrent [shetef]” (Job 38:25). There are places where they call hair shitfa. There was an incident involving a certain man who was sitting and expounding, and he said: ‘You do not have any hair for which the Holy One blessed be He did not create its own follicle, so that one would not derive benefit from that of another.’
His wife said to him: ‘Now you want to go out and seek your sustenance? Stay and your Creator will sustain you.’ He heeded her and stayed, and his Creator sustained him. “Or a path for the lightning of thunder” (Job 38:25); even for thunder that comes from the sky, the Holy One blessed be He crafts for it its own path.
Why to that extent? So it will not go out and destroy the entire world. Alternatively, “or a path for the lightning of thunder” – Rabbi Avin said: This is analogous to a vegetable garden into which a spring flows. As long as the spring flows into it, its vegetables are dark.
If the spring stops, its vegetables will grow pale. So too, if a person merits, “black hair grew in it; the scall healed, it is pure” (Leviticus 13:37). If not, “the hair in the mark turned white” (Leviticus 13:3). That is what is written: “A man [adam], if he will have,” or blood [o dam].7The word adam is used to allude to the fact that if someone has too much blood he will have leprosy. This is caused by his sins.