1 Samuel 17:14

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

1 Samuel 16:11

Then Samuel said to Jesse, “Are all your sons here?” Jesse replied, “There is still one left, the youngest; he is tending the sheep.” Samuel said to Jesse, “Send word and bring him; because we will not sit down [to eat the sacrificial meal] until he comes here.”

Genesis 25:23

The Lord said to her,

“[The founders of] two nations are in your womb;
And the separation of two nations has begun in your body;
The 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
Then Samuel said to Jesse, “Are all your sons here?” Jesse replied, “There is still one left, the youngest; he is tending the sheep.” Samuel said to Jesse, “Send word and bring him; because we will not sit down [to eat the sacrificial meal] until he comes here.”
Genesis 25:23
The Lord said to her,

“[The founders of] two nations are in your womb;
And the separation of two nations has begun in your body;
The one people shall be stronger than the other;
And the older shall serve the younger.”