Genesis 18:2

Then Abram fell on his face, and God spoke with him, saying,

Then the men rose up from there and looked down toward Sodom; and Abraham was walking with them to send them off.

Then the two angels came to Sodom in the evening as Lot was sitting in the gate of Sodom. Lot saw them and rose to meet them and bowed down with his face to the ground.

And Isaac went out to muse in the field toward evening; and he lifted up his eyes and looked, and behold, camels were coming.

Now it happened when Joshua was by Jericho, that he lifted up his eyes and looked, and behold, a man was standing opposite him with his sword drawn in his hand, and Joshua went to him and said to him, “Are you for us or for our adversaries?”

Do not neglect to show hospitality to strangers, for by this some have entertained angels without knowing it.