Joshua 5:13-15

While Joshua was near Jericho, he suddenly saw a man standing in front of him, holding a sword. Joshua went up to him and asked, “Are you one of our soldiers, or an enemy?” “Neither,” the man answered. “I am here as the commander of the LORD's army.” Joshua threw himself on the ground in worship and said, “I am your servant, sir. What do you want me to do?” And the commander of the LORD's army told him, “Take your sandals off; you are standing on holy ground.” And Joshua did as he was told.