Albert Barnes Commentary Acts 7:33

"And the Lord said unto him, Loose the shoes from thy feet: for the place whereon thou standest is holy ground." — Acts 7:33 (ASV)

Then said the Lord, etc. In Exodus 3 this is introduced in a different order, as being spoken before God said, "I am the God," etc.

Put off your shoes, etc. (Exodus 3:5). To put off the shoes, or sandals, was an act of reverence. Especially, the ancients were not permitted to enter a temple or holy place with their shoes on. Indeed, it was customary for the Jews to remove their shoes whenever they entered any house, as a mere matter of civility. Compare. See Barnes on John 13:6.

See Joshua 5:15.

Is holy ground. It is rendered sacred by the symbol of the Divine Presence. We should enter the sanctuary, the place set apart for Divine worship, not only with reverence in our hearts, but with every external indication of veneration. Solemn awe and deep seriousness become the place set apart for the service of God.