For doing what is agreeable to Bhima, Arjuna vows that he will kill in battle with his arrows this Karna with all his followers.
अर्जुनः प्रतिजानीते भीमस्य प्रियकाम्यया। कर्णं कर्णानुगांश्चैव रणे हन्तास्मि पत्रिभिः॥