If thy brother, the son of thy mother, or thy son, or thy daughter, or the wife of thy bosom, or thy friend, which is as thine own soul, entice thee secretly, saying, Let us go and serve other gods, which thou hast not known, thou, nor thy fathers; If thy brother - or thy son - The teacher of idolatry was to be put to death; and so strict was this order that a man must neither spare nor conceal his brother, son, daughter, wife, nor friend, because this was the highest offense that could be committed against God, and the most destructive to society; hence the severest laws were enacted against it.
Related Commentaries of Deuteronomy 13:6
Deuteronomy 13:6
6 If thy brother, the son of thy mother, or thy son, or thy daughter, or the wife of thy bosom, or thy friend, which is as thine own soul, entice thee secretly, saying, Let us go and serve other gods, which thou hast not known, thou, nor thy fathers;