2 Chronicles 24

Thus Joash the king did not remember the kindness which Jehoiada his father had done to him, but killed his son; and as he died, he said, “The Lord look on it, and repay!” v.22

Read chapter 24
Joash was seven years old when he became king and reigned for 40 years.  He was a "good" king all the days that he had Jehoiada the priest as his teacher and basically father figure since his father died when he was only a year old.  The sad thing is that once Jehoiada died Joash became an evil king, allowing idols again among the people of Judah and Jerusalem.  Jehoiada kept Joash from being murdered, raised him as his son, set him on the throne as the rightful king and counseled him all his days, yet Jehoiada did not remember any of this kindness and sacrifice.  The thing I can't even imagine is the murder of Zechariah (Jehoiada's son and again probably like a brother to Joash).  Zechariah stepped up and prophesied against these wicked acts of the people, but they didn't want to hear that message and commanded King Joash to have him stoned.  How often this seems of rulers listening to the people rather than God.  Joash is one of eleven rulers offended by God's servant.  Joash's end is an unfortunate one even though he may have had the majority of his rule a God-centered one.  Even his own servants turned on him in his dying moments, who may have been but slaves yet became God's executioners.  
Who are some people in your life that you don't want to forget their kindness shown you even if things are not the same as they used to be?