INDRA AND VRITRA
The earliest reference to the battle between Indra and Vritra is found in the Rigveda in which Vritra is described as the demon of drought.
Indra killed the demon and liberated water , earning the title VRITRAHAN - the slayer of Vritra.
Indra though the king of the devas, was not really very wise for most of the time he got into trouble. He easily paved way for anger, pride, envy, jealousy, arrogance and fear, like any human being. So was his nature. One day when Indra was in swarg, he was enjoying the beauty of nature around him and wondered about its daintyness and splendor. He felt very proud of it for his mind said that he is the Lord of all this beauty and also indeed the King of Kings. Indra thought that he is superior to everyone and nobody can overcome his power. As this thought was running in his mind, there entered Brihaspathi who is the preceptor of all the devas. But Indra was so much engrossed in his pride that he did not rise form his seat to receive the teacher with due respect. Brihaspathi felt very badly insulted and was offended by this arrogant behavior of Indra. So Brihaspathi immediately returned back from the court of Indra and became invisible. Only after all this happened Indra came to reality and knowing what has happened he felt very sorry and quickly went in search of the teacher, Brihaspathi. But the preceptor was not seen at all.
Simultaneoulsy there was lot of quarrel and battle happening between the asuras and devas. Unfortunately since the devas now had no teacher or preceptor to teach and guide them the right way, the deavs started losing in all their ventures. It was even more plus for the asuras, that knowing the devas have offended their teacher they took more advantage and attacked the devas more. And time and again, the devas suffered defeat and humiliation. Seeing all this Indra went to Brahma for help and when he told about the happening, Brahma was very much disappointed and said that Indra is paying the price for his own arrogancy. Brahma also told that a teacher is always to be kept in par with God and therefore he deserves all respect and need to be worshipped. Then brahma told that since Indra and devas have suffered enough because of the asuras, they can now go and meet Vishwarupa, the younger son of Twata, who is a great yogi and asked them to request Vishwarupa to be his preceptor. Vishwarupa also agreed to be their preceptor and started to guide them. The Devas now scored one sweeping victory after another. The asuras lost miserably. Amidst all this Vishwarupa who was an asura from his mother's side and a deva from his father's side offered oblations in the sacrificial fire to the devas he secretely offered a share of it to the daityas too. When Indra realized this he got very wild and went and cut off the head of Vishwarupa.
When Twasta deva heard of this, he lit a sacrificial fire, poured oblations into it and commanded a demon to arise from it, for the destruction of Indra. An awful looking creature called Vritra rose from the flames and filled the air with his hot breath. He had a flaming tongue, which would devour anything that came it's way. All the people of the three world fled in fear at the sight. But the devas took courage in their hands and attacked the monster form all sides. They used every weapon they could lay their hands on. But Vritra only swallowed them as if they were the most delicious fruits in the world. The devas were terrified. They went to Sri Narayan and asked him for help. Narayana said to Indra, "Go to the rishi Dadhichi and ask him to give his body. Then from his bones shall issue a weapon with which you will be able to cut off Vritra's head." So the Gods went to Dadhichi and asked him to give his body which had been strengthened by the constant repetition of the ‘Narayana Kavach". Dadhichi gave his body to them and the divine weapon was made. Confident of victory, they attacked Vritra who had on his side the entire host of daityas and asuras. The devas whipped the asuras completely. Indra was astonished at the strength and skill of the enemy. Then Indra got down to fight with Vritra, face to face. Vritra, when he saw the slayer of his brother, was filled with rage. Trembling with emotion he said, "I am extremely happy that, I now have you in front of me, so that I can pierce your cruel heart with my trident. You shamelessly killed my brother, who was your own Guru. Even the rakshasas condemn you for this deed of yours." "I am also fully aware that the weapon you carry in your hands has been got from the bones of Maharishi Dadhichi, and that this sacred weapon will kill me, now go ahead and do your job. I am waiting to be released from this body of mine that I may merge myself with Lord Narayana, that I may tread the path of yoga and ever be his devotee."
Indra before going ahead with killing Vritra prayed to the almighty Narayana to shower him with all blessings and strength to take Vritra's life. Vritra gave a mighty roar and hurled his flaming trident at Indra. Indra destroyed it mid- way with his divine weapon and also cut off the arm that hurled it. But Vritra did'nt give up, he still tried by all means and strength to oppose and kill Indra. In anger Vritra also shouted back to Indra saying that he should feel ashamed to kill his own preceptor and Vritra's brother.Vritra now opened wide his mouth and swallowed both Indra and his elephant and all of them thought that it was the end of Indra. But Indra still having the mighty weapon with him tore open Vritra's stomach and came out with victory. As the devas stood still watching this, the soul of Vritra entered straight into Sri Narayana, who was standing amidst them all. Thus Vritra who had always been a great devotee of Sri Narayana even in the disguise of a demon body which he had got because of a curse, still retained a spontaneous and unceasing devotion for the Lord.