Negative commandment · Lo Ta’aseh #207 of 613
For a Nazarite not to become impure through contact with a dead body
שלא ייטמא הנזיר למת
The verse · Bamidbar 6:7
לְאָבִיו וּלְאִמּוֹ לְאָחִיו וּלְאַחֹתוֹ לֹא־יִטַּמָּא לָהֶם בְּמֹתָם כִּי נֵזֶר אֱלֹהָיו עַל־רֹאשׁוֹ
“He shall not make himself unclean for his father, or for his mother, for his brother, or for his sister, when they die: because the crown of his God is upon his head.”
The Rambam’s words
For a Nazarite not to become impure through contact with a dead body, as [Numbers 6:7] states: "He may not become impure even for his father, his mother,...."
שלא ייטמא הנזיר למת, שנאמר "לאביו ולאימו . . . לא ייטמא להם, במותם" (במדבר ו,ז).
Who & when
“And this prohibition is practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Nazariteship הלכות נזירות