SB 3.3.10
kala-magadha-salvadin
anikai rundhatah puram
ajighanat svayam divyam
sva-pumsam teja adisat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Kalayavana, the King of Magadha and Salva attacked the city of Mathura, but when the city was encircled by their soldiers, the Lord refrained from killing them personally, just to show the power of His own men.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
After the death of Kamsa, when Mathura was encircled by the soldiers of Kalayavana, Jarasandha and Salva, the Lord seemingly fled from the city, and thus He is known as Ranchor, or one who fled from fighting. Actually, the fact was that the Lord wanted to kill them through the agency of His own men, devotees like Mucukunda and Bhima. Kalayavana and the King of Magadha were killed by Mucukunda and Bhima respectively, who acted as agents of the Lord. By such acts the Lord wanted to exhibit the prowess of His devotees, as if He were personally unable to fight but His devotees could kill them. The relationship of the Lord with His devotees is a very happy one. Actually, the Lord descended at the request of Brahma in order to kill all the undesirables of the world, but to divide the share of glory He sometimes engaged His devotees to take the credit. The Battle of Kuruksetra was designed by the Lord Himself, but just to give credit to His devotee Arjuna (nimitta-matram bhava savyasacin), He played the part of the charioteer, while Arjuna was given the chance to play the fighter and thus become the hero of the Battle of Kuruksetra. What He wants to do Himself by His transcendental plans, He executes through His confidential devotees. That is the way of the Lord’s mercy towards His pure unalloyed devotees.