Charles Ellicott Commentary Genesis 18:5

"and I will fetch a morsel of bread, and strengthen ye your heart; after that ye shall pass on: forasmuch as ye are come to your servant. And they said, So do, as thou hast said." — Genesis 18:5 (ASV)

Comfort ye your hearts. —Hebrew, strengthen you, the original meaning of comfort, a word formed from the Latin fortis, meaning strong or brave. The heart in Hebrew signifies the sum total of all the powers, mental and bodily, of the whole person.

After that ye shall pass on. —Coming at noon, the travellers, after rest and refreshment, would continue their journey. It is quite plain that Abraham still regarded them as passing wayfarers.

Therefore ... —Abraham thus suggests that his tent was pitched near the route so that he might exercise that hospitality which was, and continues to be, the sacred duty of an Arab sheik.