(From Ruth)

A  (11)  He that toucheth the dead body of any man shall be unclean seven days.

B  (12a)  He shall purify himself with it on the third day,

C  (12b)  and on the seventh day he shall be clean:

B’  (12c)  but if he purify not himself the third day,

A’  (12d)  then the seventh day he shall not be clean.