“Unforgiveable!”
That’s probably what Ahithophel said when he found out what David had done to his granddaughter Bathsheba and to her husband. (2 Samuel 11:3; 23:34)
By David’s actions, he had brought disgrace to Ahithophel’s granddaughter and to Ahithophel’s family name.
It certainly explains his advice to Absalom, even to the place where Absalom slept with David’s concubines (2 Samuel 11:2; 16:20-22).
It also explains why he personally, a counselor, not a warrior, wanted to lead the troops sent to kill David (12 Samuel 7:1-13).
But in the end, his refusal to forgive destroyed him.
How about you? Is there someone you need to forgive?
To forgive is to set a prisoner free and discover that the prisoner was you. — Lewis B. Smedes
Moment to Moment (Bible blog) 