Adi Parva - Sambhava Parva 39

"Vaisampayana said, 'The unfortunate Satyavati then became plunged in
grief on account of her son. And after performing with her
daughters-in-law the funeral rites of the deceased, consoled, as best she
could, her weeping daughters-in-law and Bhishma, that foremost of all
wielders of weapons. And turning her eyes to religion, and to the
paternal and maternal lines (of the Kurus), she addressed Bhishma and
said 'The funeral cake, the achievements, and the perpetuation of the
line of the virtuous and celebrated Santanu of Kuru's race, all now
depend on thee. As the attainment of heaven is inseparable from good
deeds, as long life is inseparable from truth and faith, so is virtue
inseparable from thee. O virtuous one, thou art well-acquainted, in
detail and in the abstract, with the dictates of virtue, with various
Srutis, and with all the branches of the Vedas; know very well that thou
art equal unto Sukra and Angiras as regards firmness in virtue, knowledge
of the particular customs of families, and readiness of inventions under
difficulties. Therefore, O foremost of virtuous men, relying on thee
greatly, I shall appoint thee in a certain matter. Hearing me, it
behoveth thee to do my bidding. O bull among men, my son and thy brother,
endued with energy and dear unto thee, hath gone childless to heaven
while still a boy. These wives of thy brother, the amiable daughters of
the ruler of Kasi, possessing beauty and youth, have become desirous of
children. Therefore, O thou of mighty arms, at my command, raise
offspring on them for the perpetuation of our line. It behoveth thee to
guard virtue against loss. Install thyself on the throne and rule the
kingdom of the Bharatas. Wed thou duly a wife. Plunge not thy ancestors
into hell.'

"Vaisampayana continued, 'Thus addressed by his mother and friends and
relatives, that oppressor of foes, the virtuous Bhishma, gave this reply
conformable to the dictates of virtue, 'O mother, what thou sayest is
certainly sanctioned by virtue. But thou knowest what my vow is in the
matter of begetting children. Thou knowest also all that transpired in
connection with thy dower. O Satyavati, I repeat the pledge I once gave,
viz., I would renounce three worlds, the empire of heaven, anything that
may be greater than that, but truth I would never renounce. The earth may
renounce its scent, water may renounce its moisture, light may renounce
its attribute of exhibiting forms, air may renounce its attribute of
touch, the sun may renounce his glory, fire, its heat, the moon, his
cooling rays, space, its capacity of generating sound, the slayer of
Vritra, his prowess, the god of justice, his impartiality; but I cannot
renounce truth.' Thus addressed by her son endued with wealth of energy,
Satyavati said unto Bhishma, 'O thou whose prowess is truth, I know of
thy firmness in truth. Thou canst, if so minded, create, by the help of
thy energy, three worlds other than those that exist. I know what thy vow
was on my account. But considering this emergency, bear thou the burden
of the duty that one oweth to his ancestors. O punisher of foes, act in
such a way that the lineal link may not be broken and our friends and
relatives may not grieve.' Thus urged by the miserable and weeping
Satyavati speaking such words inconsistent with virtue from grief at the
loss of her son, Bhishma addressed her again and said, 'O Queen, turn not
thy eyes away from virtue. O, destroy us not. Breach of truth by a
Kshatriya is never applauded in our treatises on religion. I shall soon
tell thee, O Queen, what the established Kshatriya usage is to which
recourse may be had to prevent Santanu's line becoming extinct on earth.
Hearing me, reflect on what should be done in consultation with learned
priests and those that are acquainted with practices allowable in times
of emergency and distress, forgetting not at the same time what the
ordinary course of social conduct is.'"