John Gill Commentary 1 Kings 17:13

"And Elijah said unto her, Fear not; go and do as thou hast said; but make me thereof a little cake first, and bring it forth unto me, and afterward make for thee and for thy son." — 1 Kings 17:13 (ASV)

And Elijah said to her, fear not

That she and her son should die, it would not be the case.

go and do as you have said :

mix her meal and her oil, and make a cake of it, and bake it.

but make of it a little cake first, and bring it to me, and after
make for you and for your son :

which was not said from a selfish spirit of the prophet, but to try the faith of the woman; and besides, as Abarbinel observes, the prophet was not only hungry and thirsty through his journey, and so required to be served first, but it was for the sake of his sustenance, that the Lord would command a blessing on the meal and oil; For this reason, if she dressed it for herself and her son first, there would have been none left for the divine blessing to descend upon.