Who Blessed Who?

What's going on in Genesis 18?

• Abraham sees three strangers. He implores them to allow him to bring water to wash their feet, rest for a while, and have something to eat. They agree, and Abraham blesses them with a meal.
• Afterwards, the LORD tells Abraham that his previously barren wife Sarah will bear a son the next year, Abraham will become a great and powerful nation, and all nations on the earth will be blessed through Abraham. The LORD states that He chose Abraham, and He will bring about for Abraham what He promised.

I wonder what would have happened if Abraham didn't stop to bless those strangers.

"Do not forget to entertain strangers, for by so doing some people have entertained angels without knowing it" (Hebrews 13:2).