What is the first great thing Avraham did after he became a Jew? The Torah tells us; the first thing he did was to welcome strangers.
Whatever you do between you and people is what you do between you and G-d. Until Avraham, G-d was a stranger in the world. Avraham’s whole thing was to bring G-d into the world. What Avraham did between him and G-d is what he did between him and people.
After Avraham entered the covenant with G-d, Avraham fixed the world; whatever a person can do, that’s what Avraham did already. After Avraham entered the covenant, his fixing began on that level where you don’t reach, where mamash everything is a stranger, it doesn’t belong here.
What Avraham did with welcoming strangers brought in G-d’s light where nothing else can reach.
Children are the greatest strangers in the world. The way Avraham was welcoming angels, he was learning how to welcome Yitzchak.
To welcome a stranger means I take you into my house and just for those few minutes that you’re in my house, to fix you on that level beyond where actions reach. It’s to the deepest, deepest depths. Do you know how deep this is? I can ask somebody to my house and give them food, but I can take somebody into my house and make them perfect for a few minutes.
The difference between blessing somebody and praying for somebody is very simple. Praying for somebody means I’m begging G-d to give it to you. If He doesn’t give it to you, the world will still exist. Blessing somebody means that if G-d doesn’t give it to you the whole world is falling apart.