1 Samuel 17:14

And David was the youngest. And the three oldest followed Saul.

1 Samuel 16:11

And Samuel said to Jesse, Are all the young men here? And he said, There remains yet the youngest, and behold, he keeps the sheep. And Samuel said to Jesse, Send and bring him, for we will not sit down until he comes here.

Genesis 25:23

And Jehovah said to her, Two nations are in your womb, and two kinds of people shall be separated from your bowels. And the one people shall be stronger than the other people, 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
And Samuel said to Jesse, Are all the young men here? And he said, There remains yet the youngest, and behold, he keeps the sheep. And Samuel said to Jesse, Send and bring him, for we will not sit down until he comes here.
Genesis 25:23
And Jehovah said to her, Two nations are in your womb, and two kinds of people shall be separated from your bowels. And the one people shall be stronger than the other people, the older shall serve the younger.