1 Samuel 17:14

And David was the youngest, the three eldest having gone after Saul.

1 Samuel 16:11

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

Genesis 25:23

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