大方便佛報恩經 6.67

6.67

「若先受三歸，作優婆塞，後若受五戒，若受八戒，若受十戒，更須三歸不？」答：「不受三歸。一切得戒，以先受三歸故。」

"If one has previously received the three refuges and become an upāsaka, and later receives the five precepts, eight precepts, or ten precepts, does one need the three refuges again or not?" Answer: "One does not receive the three refuges [again]. One obtains all the precepts, because one has previously received the three refuges."