And Moses said to Hobab the son of Reuel the Midianite, Moses' father-in-law: We are going to the place of which Jehovah said, I will give it to you. Come with us, and we will do you good. For Jehovah has spoken good concerning Israel.

This is the law of the Nazarite who has vowed his offering to Jehovah for his separation, besides that which he is able to get. According to the vow which he vowed, so he must do according to the law of his separation.