And he said,
Draw not near here: put off your shoes from your feet, for the place on which you stand is holy ground.
All Commentaries on Exodus 3:5 Go To Exodus 3
Gregory the Theologian
AD 390
And as to shoes, let him who is about to touch the holy land which the feet of God have trodden, put them off, as Moses did upon the mount, that he may bring there nothing dead; nothing to come between man and God.