The Mahabharata - pg. 309

"You are not fighting, Arjuna, as you should!" exclaimed Krishna, and jumped down in a rage from the chariot and, taking up his discus, he advanced towards the grandsire.
Bhishma saw Vasudeva approaching.
"Hail, O Lotus-eyed One!" he cried. "Blessed am I to be separated from the body by you! Come, come!"
Arjuna jumped down from the chariot and, rushing forward overtook and held Krishna, casting both his arms round him. "Stop, Krishna," he cried. "Do not break your pledge. You have promised not to use weapons in this battle. This is my work. I shall not fail. I shall send my arrows and kill the beloved grandsire myself. Pray, mount the car and take the reins."