Joshua 5:13-15 ESV
When Joshua was by Jericho, he lifted up his eyes and looked, and behold, a man was standing before him with his drawn sword in his hand. And Joshua went to him and said to him, “Are you for us, or for our adversaries?” And he said, “No; but I am the commander of the army of the LORD. Now I have come.” And Joshua fell on his face to the earth and worshiped and said to him, “What does my lord say to his servant?” And the commander of the LORD’s army said to Joshua, “Take off your sandals from your feet, for the place where you are standing is holy.” And Joshua did so.
ESV: English Standard Version 2016