and set forth customs which it is not lawful for us to receive, or to observe, being Romans.

Teaching rules of living which it is not right for us to have or to keep, being Romans.

και διδασκουσιν εθιμα, τα οποια δεν ειναι εις ημας συγκεχωρημενον να παραδεχωμεθα μηδε να πραττωμεν, Ρωμαιοι οντες.

And teach customs, which are not lawful for us to receive, neither to observe, being Romans.