Jamieson, Fausset & Brown

To him the porter openeth--that is, right of free access is given, by order of Him to whom the sheep belong; for it is better not to give the allusion a more specific interpretation [CALVIN, MEYER, LUTHARDT]. and the sheep hear his voice--This and all that follows, though it admits of important application to every faithful shepherd of God's flock, is in its direct and highest sense true only of "the great Shepherd of the sheep," who in the first five verses seems plainly, under the simple character of a true shepherd, to be drawing His own portrait [LAMPE, STIER, &c.].