1 Samuel 18:1

Overview - 1 Samuel 18
Jonathan loves David.
Saul envies his praise;
10 seeks to kill him in his fury;
12 fears him for his good success;
17 offers him his daughters for a snare.
23 David persuaded to be the king's son-in-law, gives two hundred foreskins of the Philistines for Michal's dowry.
28 Saul's hatred and David's glory increase.
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1 Samuel 18:1  (King James Version)
And it came to pass, when he had made an end of speaking unto Saul, that the soul of Jonathan was knit with the soul of David, and Jonathan loved him as his own soul.

the soul of Jonathan
The modesty, piety, and courage of David were so congenial to the character of the amiable Jonathan, that they attracted his most cordial esteem and affection; so that the most intimate friendship subsisted between them from that time, and they loved each other with pure hearts fervently. Their friendship could not be affected by the common vicissitudes of life; and it exemplifies by fact what the ancients have written on the subject; [Ten philian isoteta einai, kai mian psychen ton philon heteron auton.] "Friendship is an entire sameness, and one soul: a friend is another self."
1 Samuel 14:1-14 1 Samuel 14:45 Genesis 44:30 ; Judges 20:11 ; 1 Chronicles 12:17 ; Psalms 86:11 ; Colossians 2:2

loved him
3 ; 19:2 20:17 Deuteronomy 13:6 ; 2 Samuel 1:26 ; Proverbs 18:24