In one of his tweets mourning 98-year-old Singh's death, Modi remembered how the ageing war hero stood up to salute him despite his illness.
"Sometime back I met him, who despite his ill health tried to get up to salute even though I said no. Such was his soldier discipline," he said.
Marshal Singh, the hero of 1965 India-Pakistan war and the only Air Force officer to be promoted to five-star rank, died here this evening at a hospital here after suffering a cardiac arrest.