2 Samuel 3:6

While there was war between the house of Saul and the house of David , Abner was making himself strong in the house of Saul .

During the war between the house of Saul and the house of David, Abner had been strengthening his own position in the house of Saul.

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.