Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 208

שלא ייכנס באוהל המת, שנאמר "על נפש מת, לא יבוא" (במדבר ו,ו).

[For a Nazarite] not to enter below any roof beneath which a corpse is found, as [Leviticus 21:11] states: "He shall not come into contact with any dead body." it appears to be an error, because the passage it introduces deals with the prohibition against a High Priest's coming into contact with a corpse. Perhaps the intended prooftext is Numbers 6:6, "he may not have contact with the dead."