Cannot hate (ou dunatai misein). Because of “the law of moral correspondence” (Westcott), often in John for “inherent impossibility” (Vincent). The brothers of Jesus here belong to the unbelieving world (kosmos) which is unable to love Jesus (Joh 15:18, Joh 15:23, Joh 15:24) and which Jesus had already exposed (“testify,” marturō, Joh 5:42, Joh 5:45). This unbelieving “world” resented the exposure (Joh 3:19, cf. Joh 18:37).