"I am deeply grieved to learn about the sad demise of Qurratulain Haider. She was a great teacher and scholar. She was one of the most celebrated and prolific writers of Urdu literature. Aag Ka Dariya, her magnum opus, is a landmark novel that explores the vast sweep of time and history. In her unfortunate passing away, Urdu literature has lost a towering literary figure. She will be truly missed in literary circles in the country," he said in a written statement released by the prime minister's office.