Then, while there was a battle between the house of Saul and the house of David, Abner, the son of Ner, was reigning over the house of Saul
Other versions
King James Version
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.English Standard Version
While there was war between the house of Saul and the house of David, Abner was making himself strong in the house of Saul.New International Version
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.