The 110th mitzvah is that we are commanded that the purification of a metzora must follow the procedure given in Scripture,1 i.e. using cedar wood, hyssop, crimson wool, two birds, and well water in the manner described there. The same procedure is used to purify both people and houses, as explained in Scripture.

We have therefore explained2 that there are three procedures in the Torah to purify one who is tameh, one general and two which apply to specific types of tumah. The general one is purification [by immersion] in water [which is valid for a mikvah]. Any person who is tameh becomes tahor only after immersing in water. The second category is mei niddah [water mixed with ashes of the red heifer], which is specifically for those who have become tameh through contact with a dead body. The third category is that of cedar wood, hyssop, crimson wool, two birds, and well water, which is specifically for tzora'as.

The details of this mitzvah — i.e. the first purification3 of a metzora — are explained in tractate Negaim.