1 Samuel 17:14

David was the youngest. Now the three oldest followed Saul,

1 Samuel 16:11

And Samuel said to Jesse, “Are these all the children?” And he said, “There remains yet the youngest, and behold, he is tending the sheep.” Then Samuel said to Jesse, “Send and bring him; for we will not sit down until he comes here.”

Genesis 25:23

The Lord said to her,
Two nations are in your womb;
And two peoples will be separated from your body;
And one people shall be stronger than the other;
And 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 these all the children?” And he said, “There remains yet the youngest, and behold, he is tending the sheep.” Then Samuel said to Jesse, “Send and bring him; for we will not sit down until he comes here.”
Genesis 25:23
The Lord said to her,
Two nations are in your womb;
And two peoples will be separated from your body;
And one people shall be stronger than the other;
And the older shall serve the younger.”