Reference for Keritot 44:19

אלא דכולי עלמא אין גזירה שוה למחצה

Is it not definitely established that a hekkesh cannot be applied partially? - All agree that a hekkesh cannot be applied partially, but here the Rabbis maintain that the textual analogy founded upon the common term 'mitzwoth' supersedes the hekkesh.

Jastrow