1 Samuel 18:3

Then Jonathan and David made a covenant, because he loved him as his own soul.

1 Samuel 20:8-17

Therefore you shall deal kindly with your servant; for you have brought your servant into a covenant of the LORD with you: nevertheless, if there be in me iniquity, slay me yourself; for why should you bring me to your father?

1 Samuel 20:42

And Jonathan said to David, Go in peace, since as we have sworn both of us in the name of the LORD, saying, The LORD be between me and you, and between my descendants and your descendants forever. And he arose and departed: and Jonathan went into the city.

1 Samuel 23:18

And they both made a covenant before the LORD: and David abode in the forest, and Jonathan went to his house.

2 Samuel 9:1-3

And David said, Is there yet any that is left of the house of Saul, that I may show him kindness for Jonathan's sake?

2 Samuel 21:7

But the king spared Mephibosheth, the son of Jonathan the son of Saul, because of the LORD's oath that was between them, between David and Jonathan the son of Saul.

Treasury of Scripture Knowledge

Summary

Then Jonathan and David made a covenant, because he loved him as his own soul.

Bible References

General references

Genesis 21:32
Thus they made a covenant at Beersheba: then Abimelech rose up, and Phicol the chief captain of his host, and they returned into the land of the Philistines.
1 Samuel 23:18
And they both made a covenant before the LORD: and David abode in the forest, and Jonathan went to his house.
Proverbs 17:17
A friend loves at all times, and a brother is born for adversity.