וַיְהִ֗י בִּֽהְיוֹת֙ הַמִּלְחָמָ֔ה בֵּ֚ין בֵּ֣ית שָׁא֔וּל וּבֵ֖ין בֵּ֣ית דָּוִ֑ד וְאַבְנֵ֛ר הָיָ֥ה מִתְחַזֵּ֖ק בְּבֵ֥ית שָׁאֽוּל׃
And it came to pass, while there was war between the house of Saul and the house of David, that Abner showed himself strong in the house of Saul.
Read halakhic rulings (Jewish law) on II Samuel 3:6: and classical halakhic sources.