Negaim 6:1

The minimum size of a white spot is that of a square Cilician split bean. A split bean is the size of nine lentils. A lentil is the size that it takes four hairs to grow. Therefore, the minimum size of a white spot is the space that takes 36 hairs to grow.

Negaim 6:2

If a white spot was the size of a split bean and in it there was healthy flesh the size of a lentil, then if the white spot increased in size, it is unclean but if it reduced in size, it is clean. If the healthy flesh increased in size, it is unclean but if it reduced in size, it is clean.