Something in Man’s heart has always pulled him toward God, so it’s not strange that, along with the sacrifices and ordnances God required His people to observe, a man or woman could voluntarily set aside a period of time to consecrate themselves to God in what they called a vow of a Nazarite (Numbers 6). Nobody was required to take such drastic measures, but God knew there would be those whose hearts led them to draw closer, so He included the Nazarite experience in Moses’ Law.
God is always willing for men to come close, but the first thing God does when He invites folks to “separate themselves unto the LORD,” is to demand that the one accepting His invitation “separate himself” from a whole list of things.
Accept His invitation to draw closer and immediately the discussion shifts from the general to the personal. The invitation is to the whole crowd, the themselves, but the demand is hung upon the individual, the himself.