Abraham welcomed three visitors in Genesis 18 NIV
1 Then the LORD appeared to Abraham by the Oaks of Mamre in the heat of the day, while he was sitting at the entrance of his tent. 2And Abraham looked up and saw three men standing nearby. When he saw them, he ran from the entrance of his tent to meet them and bowed low to the ground. 3“My lord,” said Abraham, “if I have found favor in your sight, please do not pass your servant by.
A chapter later, Lot similarly welcome two visitors in Genesis 19:
1 Now the two angels arrived at Sodom in the evening, and Lot was sitting in the gateway of the city. When Lot saw them, he got up to meet them, bowed facedown, 2and said, “My lords, please turn aside into the house of your servant; wash your feet and spend the night.
When did they know these visitors were angels?