רבינו בחיי — זאת תורת העולה

Q — Why is the olah burned all night until morning — what does the timing add to a kapparah for the עולה ברוח (the thought-sin)?

A — Rabbeinu Bachya reads the night-burning as precise mitigation timing. The olah, RBB explains (against the chatas and asham which atone for actions), atones davka for thought-sins — the iconic case being Iyov, who brought olos because "אולי חטאו בני וברכו אלקים בלבבם". And the זמן of thought-sins is night: "חושבי און ופועלי רע על משכבותם" (Mishlei) — a man plans transgressions on his bed at night, then executes them by day. So the kapparah must run when the aveirah is being formulated, not after it has already been done. The olah burns from evening until morning because it is intercepting the chet at the very stage of its conception — burning up the thought-fuel before it can become a daytime act. The morning ash is not the residue of a finished sin but of an unborn one.