Commentary for Taanit 52:17
מתקיף לה אבוה דרבי זירא ואמרי לה אושעיא בר זבדא אי מה נזיר אסור בחרצן אף כהן מברך אסור בחרצן א"ר יצחק אמר קרא לשרתו ולברך בשמו מה משרת מותר בחרצן אף כהן מברך מותר בחרצן
The father of R'Zera, and some say Oshaiah B'Zabbda, demurred to this: [If that is so], then just as the Nazirite is forbidden to eat the shells<span class="x" onmousemove="('comment',' Or 'kernels'.');"><sup>14</sup></span> [of grapes], so too should the priest about to recite the priestly benediction be forbidden [to eat] the 'shells of grapes'. -R'Isaac replied: Scripture says, To minister unto Him and to bless in His name;<span class="x" onmousemove="('comment',' Deut. X, 8.');"><sup>15</sup></span> [from this is to be inferred] that just as the officiating priest may e the shells [of grapes]<span class="x" onmousemove="('comment',' Scripture forbids expressly the drinking of wine only. Cf. Lev. X, 9.');"><sup>16</sup></span> so too may the priest about to recite the priestly benediction.