'Brothers' in the Bible

But Joab and Abishai [Asahel’s brothers] pursued Abner. When the sun was going down, they came to the hill of Ammah, which is in front of Giah on the way to the wilderness of Gibeon.

Then Abner was very angry at the words of Ish-bosheth, and he said, “Am I a dog’s head [a despicable traitor] that belongs to Judah? Today I show loyalty and kindness to the house of Saul your father, to his brothers and his friends, by not having you handed over to David; and yet you charge me today with guilt concerning this woman.