1 Samuel 20:17

And Jonathan caused David to swear again, because he loved him: for he loved him as he loved his own soul.

1 Samuel 18:1

And it came to pass, when he had finished speaking unto Saul, that the soul of Jonathan was knit with the soul of David, and Jonathan loved him as his own soul.

1 Samuel 18:3

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

Deuteronomy 13:6

If your brother, the son of your mother, or your son, or your daughter, or the wife of your bosom, or your friend, who is as your own soul, entices you secretly, saying, Let us go and serve other gods, which you have not known, you, nor your fathers;

2 Samuel 1:26

I am distressed for you, my brother Jonathan: very pleasant have you been unto me: your love to me was wonderful, passing the love of women.

Proverbs 18:24

A man that has friends must show himself friendly: and there is a friend that sticks closer than a brother.

Treasury of Scripture Knowledge

Summary

And Jonathan caused David to swear again, because he loved him: for he loved him as he loved his own soul.

General references

Bible References

Because he loved him

1 Samuel 18:1
And it came to pass, when he had finished speaking unto Saul, that the soul of Jonathan was knit with the soul of David, and Jonathan loved him as his own soul.
Deuteronomy 13:6
If your brother, the son of your mother, or your son, or your daughter, or the wife of your bosom, or your friend, who is as your own soul, entices you secretly, saying, Let us go and serve other gods, which you have not known, you, nor your fathers;
2 Samuel 1:26
I am distressed for you, my brother Jonathan: very pleasant have you been unto me: your love to me was wonderful, passing the love of women.
Proverbs 18:24
A man that has friends must show himself friendly: and there is a friend that sticks closer than a brother.

General references

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.