משנה אויף רות 2:19

A yavam [who is a priest] does not allow [his sister-in-law] to eat terumah. If she had spent six months waiting for her husband and six months waiting for the yavam, or even [if she spent] all of them waiting for her husband less one day waiting for the yavam, or all of them waiting for the yavam less one day waiting for her husband, she may not eat terumah. This [was the ruling according to] the first mishnah. The court that followed afterwards ruled: a woman may not eat terumah until she has entered the bridal chamber.