1 Samuel 17:14

David was the youngest. The three eldest followed Saul,

1 Samuel 16:11

Then Samuel said to Jesse, "Are all your sons here?" And he said, "There remains yet the youngest, but behold, he is keeping the sheep." And Samuel said to Jesse, "Send and get him, for we will not sit down till he comes here."

Genesis 25:23

And the LORD said to her, "Two nations are in your womb, and two peoples from within you shall be divided; the one shall be stronger than the other, the older shall serve the younger."

Treasury of Scripture Knowledge

Summary

And David was the youngest: and the three eldest followed Saul.

Bible References

The youngest

1 Samuel 16:11
Then Samuel said to Jesse, "Are all your sons here?" And he said, "There remains yet the youngest, but behold, he is keeping the sheep." And Samuel said to Jesse, "Send and get him, for we will not sit down till he comes here."
Genesis 25:23
And the LORD said to her, "Two nations are in your womb, and two peoples from within you shall be divided; the one shall be stronger than the other, the older shall serve the younger."

The Holy Bible, English Standard Version® copyright © 2001 by Crossway Bibles, a publishing ministry of Good News Publishers.