1 Samuel 18:3

And Jonathan maketh -- also David -- a covenant, because he loveth him as his own soul,

1 Samuel 20:8-17

and thou hast done kindness, to thy servant, for into a covenant of Jehovah thou hast brought thy servant with thee; -- and if there is in me iniquity, put thou me to death; and unto thy father, why is this -- thou dost bring me in?'

1 Samuel 20:42

and Jonathan saith to David, 'Go in peace, in that we have sworn -- we two -- in the name of Jehovah, saying, Jehovah is between me and thee, and between my seed and thy seed -- unto the age;' and he riseth and goeth; and Jonathan hath gone in to the city.

1 Samuel 23:18

And they make a covenant both of them before Jehovah; and David abideth in the forest, and Jonathan hath gone to his house.

2 Samuel 9:1-3

And David saith, 'Is there yet any left to the house of Saul, and I do with him kindness because of Jonathan?'

2 Samuel 21:7

and the king hath pity on Mephibosheth son of Jonathan, son of Saul, because of the oath of Jehovah that is between them, between David and Jonathan 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
And they make a covenant in Beer-Sheba, and Abimelech riseth -- Phichol also, head of his host -- and they turn back unto the land of the Philistines;
1 Samuel 23:18
And they make a covenant both of them before Jehovah; and David abideth in the forest, and Jonathan hath gone to his house.
Proverbs 17:17
At all times is the friend loving, And a brother for adversity is born.