וַתְּהִ֤י הַמִּלְחָמָה֙ אֲרֻכָּ֔ה בֵּ֚ין בֵּ֣ית שָׁא֔וּל וּבֵ֖ין בֵּ֣ית דָּוִ֑ד וְדָוִד֙ הֹלֵ֣ךְ וְחָזֵ֔ק וּבֵ֥ית שָׁא֖וּל הֹלְכִ֥ים וְדַלִּֽים׃ (ס)
Now there was long war between the house of Saul and the house of David; and David waxed stronger and stronger, but the house of Saul waxed weaker and weaker.
Read Kabbalistic (mystical) interpretations of II Samuel 3:1: Zohar and classical Jewish mystical sources, free online.