John Lightfoot on John 10:3

[The porter.] I am mistaken if the servants that attend about the flock under the shepherd are not called by the owner of them, Ecclesiastes 12:11, those that fold the sheep: at least if the sheepfold itself be not so called. And I would render the words by way of paraphrase thus: "The words of the wise are as goads, and as nails fastened by those that gather the flock into the fold: goads, to drive away the thief or the wild beast; and nails, to preserve the sheepfold whole and in good repair: which goads and nails are furnished by the chief shepherd, the master of the flock, for these uses." Now one of these servants that attended about the flock was called the porter. Not that he always sat at the door; but the key was committed to his charge, that he might look to it that no sheep should stray out of the fold, nor any thing hurtful should get or be let in.