The word "brothers" refers to men and women believers. Alternate translation: "left the fellow believers" (See: [[rc://en/ta/man/jit/figs-gendernotations]])
This is a symbolic action that indicates that he had done something he had vowed to do. This can be stated in active form. Alternate translation: "he had someone cut off the hair on his head" (See: [[rc://en/ta/man/jit/translate-symaction]] and [[rc://en/ta/man/jit/figs-activepassive]])