'Brethren' in the Bible

"Do not cling to me," said Jesus, "for I have not yet ascended to the Father. But take this message to my brethren: 'I am ascending to my Father and your Father, to my God and your God.'"

Hence the report spread among the brethren that that disciple would never die. Yet Jesus did not say, "He is not to die," but, "If I desire him to remain till I come, what concern is that of yours?"