וַיֹּ֥אמֶר יְהוֹנָתָ֖ן אֶל־דָּוִ֑ד מַה־תֹּאמַ֥ר נַפְשְׁךָ֖ וְאֶֽעֱשֶׂה־לָּֽךְ׃ (פ)
Then said Jonathan unto David: ‘What doth thy soul desire, that I should do it for thee?’
Read halakhic rulings (Jewish law) on I Samuel 20:4: and classical halakhic sources.