Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 206
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 206, with English translation by Maimonides (Rambam).
שלא יאכל זוגין, שנאמר "ועד זג--לא יאכל" (במדבר ו,ד).
[For a Nazarite] not to eat grape peels, as [Numbers, ibid.] continues: "He shall not eat [anything from wine grapes,...] to its peels."