Sri Sathya Sai Speaks, Vol 29 (1996)
Story - Excerpt from Divine Discourse
Vedanta is Very Easy to Practise (Alternative Translation)

The Mahabharata war was to start on the new moon day (amavasya). Arjuna was totally dejected and depressed on seeing the formations of Kaurava and Pandava armies a day prior to amavasya, i.e. Chaturdasi. Earlier, it was Arjuna himself who had insisted that they were ready to fight the battle with the Kauravas and said that Krishna should not go to the Kaurava court on a peace mission. The same Arjuna was very nervous when the war was actually to commence.
Krishna wanted to impart the knowledge of the Bhagavad Gita to Arjuna to instil courage and enthusiasm in him. But before imparting this knowledge, Krishna wanted to test Arjuna, to see whether he had total faith in Him.
Krishna took Arjuna to a forest. While returning, it became dark. Krishna pointed to a bird perched on a tree and said, "Arjuna, see how beautiful this peacock is!" He started this conversation to see the state of Arjuna's mind.
Arjuna replied, "Yes, Swami, the peacock in really beautiful." Krishna said, "Oh madcap, that is not a peacock. Don't you see it is an eagle?" Arjuna replied, "Yes, Swami, it is an eagle." Krishna slapped him on his back and said, "What a fool you are, Arjuna, that you are unable to make out whether it is a peacock, an eagle, or some other bird. Look carefully. It is neither a peacock nor an eagle. It is a pigeon." Arjuna replied, "Yes, Swami, it is a pigeon."
Pretending to be a little angry, Krishna said, "Don't you have common sense? Don't you have discrimination power? What are you thinking? You don't seem to enquire whether it is a peacock or an eagle or a pigeon. You are blindly saying yes to whatever I say."
Arjuna replied, "Oh Krishna, if I say it is not a peacock, You may change it into a peacock. Similarly, if I say it is not an eagle or a pigeon, You may turn it into any of them. You can do anything. Your word is important for me. What does it matter to me whether it is a pigeon or a peacock or an eagle?" Krishna was very happy that Arjuna had so much faith in His words. He placed His hand on Arjuna's head and blessed him, saying, "Now you are My true devotee." Fix your mind on Me, be devoted to Me, offer obeisance to Me and worship Me.