There was a king named Mahabhisha. This king was very religious, this king had done many pious deeds and was very famous among other kings. This king performed many yjnas and hundred Ashwamedha Yagyas, as a result of which this king was become eligible to go heaven and later he went to heaven and lived there happily.
One day a meeting of Brahma Ji was going on in which all the gods were there. King Mahabhisha was also present in that meeting due to the strength of his religious deeds. At the same time, Ganga came there, after some time, the wind started blowing and the clothes of Ganga fell from her body partially . All the gods, thinking that Ganga should not be seen in this condition, turned their eyes down. King Mahabhisha, who was a great king, did not lower his eyes, he was very fascinated to see Ganga ji and started to stare ganga in the middle of that meeting. In that meeting of brahma where were present , Goddess Ganga was also looking towards King Mahabhisha. Both these were fascinated, so could not stop staring at each other.
When Brahma ji saw that Mahabhisha and Ganga ji are looking at each other in this way and all the gods are standing with their eyes down , in great anger Brahma ji cursed King Mahabhisha for his arrogance that the king should be born in human form in on earth and when he earns virtue by doing religious deeds there, only then he will be able to come to heaven again. Brahma also said to Ganga ji, Devi, you are an equal participant in this act, that is why you too take birth as a human being.
Due to this curse, Mahabhisha king became Shantanu after taking birth in human form and Ganga ji also took the form of human. One day when King Shantanu went to the banks of Ganga on the pretext of hunting, then Ganga also came there in human form. After seeing Shantanu, Ganga recognized that this is king Mahabhisha who is born in human form. Seeing him, Ganga remembered her love affair with him in former times. Shantanu was also fascinated to see Ganga and asks her to marry him as promised by him to his father.
Ganga ji immediately agreed. Ganga ji placed a condition in front of Shantanu that if you ask me any question or if you ever ask me the reason for my deeds, I will leave you. The king accepted these conditions and married Ganga. King Shantanu and Ganga ji had seven sons who were immersed in water by ganga as soon as they were born, who were cursed Vasus, the king, fearing that ganga would leave him and go away, never stopped Ganga. But at the time of the eighth son, the king stopped ganga , so Ganga went away with that child. who later became known as Bhishma was also a cursed Vasu.
Thus Ganga ji was married to the Shantanu king.