Hey Ram

The movie begins at present day with Saket Ram (Kamal Hassan), an 89-year-old South Indian Brahmin who is dying. The scene reverts to the past as Saket remembers the 1940s, when he and his good friend, were archaeologists working together under their boss, Mortimer Wheeler, in Mohenjo-daro (Indus Valley Civilization) in Karachi. Relations are pleasant between the Indians and the English, and Saket and Amjad do not approve of Partition and the creation of Pakistan.Aparna Ram (Rani Mukerji), Saket's simple Bengali wife, is a school teacher. She lives in Calcutta in the midst of riots and chaos over the issue of the formation of Pakistan and the call by Mohammad Ali Jinnah for "Direct Action". Saket goes to Calcutta and is swept into the madness. In one instance, Saket saves an innocent Sikh girl from the hands of a barbaric Muslim gang. When he returns to his house, he finds a group of Muslims entering his house. They brutally rape and murder Aparna. Saket, unable to cope with his tragic loss, kills the Muslims who raped and killed his wife in a fit of rage.Outside his house, he runs into another Brahmin, Sriram Abhyankar (Atul Kulkarni), who is part of a Hindu militant group determined to fight the Muslims' malice with similar brute force, and assassinate Gandhi for what they perceive to be his treachery towards Hindu dominated India (Gandhi wanted Hindus and Muslims to co-exist peacefully with hope of winning over the hearts of the rioters through sheer self-pity). However, Abhyankar and his fellow extremists had lost patience at what they deemed Mahatma Gandhi's unreasonable stand to appease Pakistan, who had already invaded Kashmir by that time. Gandhi was pressurizing the newly founded Indian state to pay Rs. 62 Crore to Pakistan and some territorial concessions as well.Urged by family to remarry, he weds Mythili (Vasundhara Das). However, on a trip to Maharashtra, he reunites with Abhyankar and becomes a part of his militant organisation that plots to do away with Gandhi. Due to an horse-riding accident, Abhyankar is left a quadriplegic and has Ram swear that he will carry on his work, that of killing the Mahatma.Saket comes to the belief that Mahatma Gandhi (Naseeruddin Shah) is solely responsible for the division of India and of the two religions and also of having supported whom they viewed as the enemy. Hindu fundamentalists, including Saket, are furious and plot to murder Gandhi. However, Saket, after several incidents surrounding and leading to Amjad's death (with whom he reunites briefly in a congested Delhi area), changes his mind about Gandhi. He decides against assassinating the leader, and attempts to beg for forgiveness. Soon afterwards, Gandhi is killed by another assassin, Nathuram Godse. Ironically, Gandhi dies without his famous last words: "Hey Ram!" as popularly believed, and as in Richard Attenborough's film Gandhi (film).(Though actual witnesses have denied having heard Gandhi utter those famous last words.)Then on, Saket Ram lives by Gandhian principles. As the 89-year-old Saket Ram is being taken to the hospital, he is told of bomb blasts in the city due to Hindu-Muslim communal riots. He asks "Innuma(even still)?". They were forced by the police to be taken into an underground shelter for their security, but Saket Ram dies there. in his funeral gandhis grandson come and see saket private room with full of historical photos. Saket's grandson handed over gandhis footwears and spectacles which Saket collected from place of shoot out and keep like inspirational treasure.Thanks to Wikipedia

Question: Who makes Saket swear that he will kill Mahatma Ghandi?