Abner made himself strong, &c. He used his utmost endeavours to support Saul's house, going up and down through all the tribes of Israel to strengthen Ish-bosheth's interest, and confirm the people in their allegiance to him: which is mentioned to show the reason of Abner's deep resentment of the following aspersion.
Related Commentaries of 2 Samuel 3:6
2 Samuel 3:6
6 And it came to pass, while there was war between the house of Saul and the house of David, that Abner made himself strong for the house of Saul.