We are commanded that the purification process for tzaraat, whether the sort that afflicts humans or the sort that afflicts houses, should be through the procedure detailed in the Torah. This procedure includes the taking of [a piece of wood from a] cedar tree, hyssop, crimson thread, two birds, and well water. Then we do with these items all that the Torah prescribes, after which the individual or the house is purified.

[For the human metzora,] this is the first step of the purification process. [See Positive Commandment 111 for the second and final step.]