PURPORT

Bhagavad-gita mentions five causes of defeat or victory. Of these five, daiva (providence) is the most powerful (na ca daivat param balam). Bali Maharaja knew the secret of how he had formerly been victorious because providence was in his favor. Now, since that same providence was not in his favor, there was no possibility of his victory. Thus he very intelligently forbade his associates to fight.