Humayun was the oldest son of the great Mughal Emperor Babar. Once he was taken seriously ill. The court physicians treated him with great care and attention. But the more they tried to restore his health, the worse he became. At last the anxious father called a meeting of his best friends in order to seek their counsel. They advised him to sacrifice his dearest possession for the sake of his son. They referred to the Koh-i-Noor diamond ( later English took this diamond to England in order to fit it in the crown of the Queen). But he said that his own life was more precious than that. So he went thrice round the patient's bed praying that he might fall ill in place of his son. And his prayer was granted by God.. The Emperor Babar fell ill, and Humayun began to feel better day by day. At last the son recovered fully, and his loving father passed away.