A La Lache League Leader told me this years ago (10?) when my son began
biting and its been working for my moms ever since-

Pay careful attention to what baby is doing with his tongue. The baby will
not bite his own tongue, so the tongue pulls back before he bites. Mom can
feel the change and stick her finger in baby's mouth. Then gently say *don't
bite* and end the feeding, putting the baby down. If his feeding and holding
ends every time he bites he will learn not to bite mom.

Believe it or not one or two times does the trick
Marie Davis, RN, IBCLC