Raghuvanshs king Mahabhish reborn as king Shantanu.
One of the King from Ikshwakukul thats Raghuvansh, Ramjis vansh named MAHABHISH or Mahabhishak ruled according to truth and justice and was rewarded with heaven upon his death. Once, while he was seated in the court of Indra, the king of heaven,the Goddess Ganga (she is the goddess of the sacred river Ganges), happened
to visit there. Due to a passing breeze, her dress got rearranged. All those present at the court averted their eyes out of respect for the Goddess. However, Mahabhishak, who was enamored by her beauty, kept staring at her.This angered Lord Brahma. He cursed Mahabhishak saying, "Mahabhishak, since you kept staring at Ganga when she was in a compromising position, I curse you to be reborn as a king . Ganga will be your wife there and will torment you by her actions and cause you much grief."
Story of Rishi Vashishth cursed Vasu:
Meanwhile, the eight Vasus, who were celestial brothers who resided in heaven, happened to offend the sage Vasishta .The eldest of them was Dhyou. The sage cursed them to be born as mortals and suffer.
Vasishta, the son of Brahma was a great sage. . He had his hermitage on Mt. Meru, and this spot was very beautiful and secluded. He
possessed a cow called Nandini, which was the daughter of Surabhi, by he sage Kashyapa. (Here, Surabhi is Kamadhenu). This cow, like her mother, was capable of yielding great riches to its possessor. It was in the habit of roaming the woods near the hermitage of the Rishi.
One day, the celestial Vasus came to this spot, accompanied by their wives. They were eight brothers, who normally lived in the heaven. When one of the ladies beheld Nandini, the cow of plenty, she became desirous of possessing it. She said to her husband Dyu, "My Lord, I wish to obtain this cow for my friend. My friend Jitavati, the daughter of the sage Usinara, is mortal. By drinking the milk from this cow regularly, she will be free from disease and decrepitude. Get this cow for me."
Now the Vasu knew that the cow belonged to the Rishi. So he tried to
persuade his wife to forget about the cow, for the Rishi would not part with it under any circumstances. However, unable to bear the nagging of his wife, he ultimately decided to carry the cow away by force. Assisted by his brothers, he took the cow away to his home.
Rishi Vasishta had been away from his hermitage at this time. When he got back, he was surprised to see that his cow had not returned, long past its usual time. He searched the nearby woods and saw no sign of the cow. He then used his Yogic power and divined all that had taken place. He then cursed the Vasus, saying, "Since in their arrogance the Vasus have committed the sin of stealing a Brahmana's property, may they be born on earth and suffer a mortal's fate!".
When the Vasu's came to know of the Rishi's curse, they became penitent, and begged the Rishi to save them from his curse. At last, the sage relented. He said, "My curse cannot be completely stayed. The seven of you who have merely obeyed your brother's orders, shall not have to suffer the mortal fate for long. However, Dyu, who is really the author of this mischief, will have to suffer his curse for a long time. However, he shall be an illustrious warrior, and will not have any children." will have to live for a long time as a mortal, and suffer for his sins. You must know that the river Ganga is fated to be the wife of Shantanu, who was Mahabhishak in his previous birth. All of you will be born as their sons."