Devavratha (Bhishma)’s father Shantanu wanted to marry a fisherwoman Satyavati. Satyavati’s father had refused to give his daughter’s hand to Shantanu on the grounds that his daughter’s children would never be rulers. Devavratha (Bhishma) took oath that he would never stake a claim to the throne, implying that the child born to Shantanu and Satyavati would become the ruler after Shantanu. Devavratha (Bhisma) also took the vow of lifelong celibacy, thus sacrificing his ‘crown-prince’ title and denying himself the pleasures of conjugal love. This gave him immediate recognition among the gods. His father granted him the boon of Ichcha Mrityu (control over his own death — he could choose the time of his death, making him immortal till his chosen time of death, instead of completely immortal which would have been an even more severe curse and cause of suffering).