John Gill 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)

And I will fetch a morsel of bread
A piece or a loaf of bread, as De Dieu shows the word signifies; bread being put for all the necessaries of life:

and comfort you your hearts ;
eat to refresh your spirits and renew your strength, that you may be able to pursue your journey: and

after that you shall pass on
your way; I will retard you no longer:

for therefore are you come to your servant ;
not that he thought they came this way on purpose to take some refreshment with him, but so it was ordered by the providence of God; and since it was, he desires that they would accept of his invitation:

and they said, so do as you have said ;
they agreed to it, that water should be fetched to wash their feet, and food for them to eat.