A.T. Robertson Commentary John 10:5

"And a stranger will they not follow, but will flee from him: for they know not the voice of strangers." — John 10:5 (ASV)

A stranger (αλλοτριω). Literally, "One belonging to another" (from αλλος, opposed to ιδιος). A shepherd of another flock, it may be, not necessarily the thief and robber of verse 1. Note associative instrumental case after ακολουθησουσιν (future active indicative of ακολουθεω, verse 4). Note the strong double negative ου μη here with the future indicative, though usually with the aorist subjunctive (Aleph L W have it here). They simply will not follow such a man or woman, these well-trained sheep will not.

But will flee from him (αλλα φευξοντα απ' αυτου). Future middle of φευγω and ablative case with απο. They will flee as if from a wolf or from the plague. Alas and alas, if only our modern pastors had the sheep (old and young) so trained that they would run away from and not run after the strange voices that call them to false philosophy, false psychology, false ethics, false religion, false life.