One of King David's best leader qualities was his willingness to be approachable. When David learned that his men had bravely fought and defeated David's son, Absalom, David mourned Absalom's death but didn't praise his men for their victory. 

Joab knew this would undermine David's leadership. In 2 Samuel 19, Joab said to David, "Today you have shamed all your servants, who have saved your life today and the lives of your sons and daughters, … by loving those who hate you, and by hating those who love you."  

David heeded Joab's instruction and encouraged his men in their victory. 

Many leaders over time think they have all the answers and are unwilling to listen to others. Being humble and approachable is critical for hearing the necessary truths from others.