en_tn/1sa/18/01.md

the soul of Jonathan was bound to the soul of David

Very close friendship is spoken of as if it were binding together the souls of two people. This can be stated in active form. Alternate translation: "Jonathan felt a strong affection towards David" or "Jonathan committed himself to David" (See: rc://en/ta/man/jit/figs-metaphor and rc://en/ta/man/jit/figs-activepassive)

Jonathan loved him as his own soul

Here "loved" refers to the love between friends, not romantic love. The word "soul" represents the person or the person's life. Alternate translation: "Jonathan loved David as much as he loved himself" or "Jonathan loved David as he loved his own life" (See: rc://en/ta/man/jit/figs-synecdoche)