P arshas Tazria-Metzora
“And the person to be cleansed shall take two live clean birds a cedar stick a strip of crimson [wool] and hyssop.” (Vayikra 14:4)
Rashi says he takes cedar wood to symbolize his arrogance and hyssop to humble himself.
However why should cedar wood — symbolizing his arrogance — be part of his penance?
It’s essential that his humility come about by recognizing that he was arrogant. He thought he was “something” and had what to be proud of but this shows him that he was actually “nothing” — he was low like a worm [based on the literal translation of “tolaas-strip of crimson”]. A person must realize that everything’s from Hashem and if he’s missing this essential knowledge then all is worthless. (Sfas Emes al HaTorah)