E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
David and Jonathan.
Inseparable friends. Similar examples of friendship were Pylads and Orests (q.v.); Damon and Pythias (q.v.); etc.
1
I am distressed for thee, my brother Jonathan. Very pleasant hast thou been to me. Thy love to me was wonderful, passing the love of women.2 Sam. i. 26.