וַיֵּצֵ֤א יוֹאָב֙ מֵעִ֣ם דָּוִ֔ד וַיִּשְׁלַ֤ח מַלְאָכִים֙ אַחֲרֵ֣י אַבְנֵ֔ר וַיָּשִׁ֥בוּ אֹת֖וֹ מִבּ֣וֹר הַסִּרָ֑ה וְדָוִ֖ד לֹ֥א יָדָֽע׃
And when Joab was come out from David, he sent messengers after Abner, and they brought him back from Bor-sirah; but David knew it not.
Read halakhic rulings (Jewish law) on II Samuel 3:26: and classical halakhic sources.