It is true that Vasudev saved infant Krishna from Kansa by taking him from the prison and placing him in Yashoda’s lap. However, as Krishna began to grow up in Gokul, Kansa made more plans of having him killed. He dispatched many demons in disguise to bring about the death of Krishna.
One of these demons was Kesi. Kesi assumed the form of a gigantic horse for the task. He galloped so fast that he could hardly be seen, his hooves touched the ground with such force that the roads cracked. His neighing was terrifying to people.
Kesi went around wreaking havoc in Gokul until Krishna challenged him to a duel. Kesi roared like a lion and charged towards Krishna and struck him with his hooves. Krishna caught hold of his hooves and tossed him to the ground. After this Kesi attacked Krishna by devouring his arm.
However, as soon as Krishna’s hand went inside Kesi’s mouth, all of Kesi’s teeth fell off and Krishna’s arm enlarged in size. Finally, Kesi died a painful death by choking on Krishna’s arm. The Gods and Narad extolled him for this deed and prophesized many other wonderful things that he would go on to do, including putting an end to Kansa and his tyranny.