Sukracharya warns Mahabali not to give land to Vamana. He says that Vamana is none other than Vishnu Himself. But Bali says that if indeed Vamana is Vishnu, then it is an honour for Bali to be asked to give something to Him. Sukracharya, taking the form of a bee, blocks the outlet in the vessel of water, for without the pouring of water, no ‘daana’ is complete. Vishnu uses a blade of grass to poke Sukracharya’s eye and blinds him. Periyazhvar, describing this incident, lauds the Lord as the One with the Sudarsana in His hand. The Lord did not use His discus, but used a piece of grass. Periyazhvar speaks of Sudarshana in this context to show that whatever the Lord uses as a weapon, Sudarsana is present in it, said M.A. Venkatakrishnan, in a discourse.
Sukracharya was only telling the truth when he warned Bali about Vamana. Not a word of what he said was untrue. Vamana was indeed Vishnu, and He had indeed come to deprive Bali of territory over which he was ruling. So, why was Sukracharya punished for being honest? Why did he lose an eye? This was a question once posed by a sishya to his guru. The latter answered that it was a sin to stop ‘daana’, and that is what Sukracharya had attempted. That is why he was punished. Then the sishya asked, “If, as you say, ‘daana’ is so virtuous, why was Bali punished? After he only gave to Vamana.”
The guru replied, “It is important to obey one’s guru, because he always has his sishya’s welfare in mind. Sukracharaya advised Bali not to trust Vamana and tried his best to prevent him from giving land to Vamana. But Bali paid no attention to his guru. So, for the sin of disobeying his guru, he was punished.” So, for every sin, there is some punishment. No one can escape the consequence of his or her actions.