Mahabharata 1.94.78

1.94.78

idaṃ me matamādatsva satyaṃ satyavatāṃ vara |
naiva jāto na vājāta īdṛśaṃ vaktumutsahet || 78 ||

"Vaisampayana continued, 'O thou of Bharata's race, Devavrata, having heard these words, and moved by the desire of benefiting his father thus answered in the hearing of the assembled chiefs, 'O foremost of truthful men, listen to the vow I utter! The man has not been or will not be born, who will have the courage to take such a vow! I shall accomplish all that thou demandest! The son that may be born of this maiden shall be our king.' Thus addressed, the chief of the fishermen, impelled by desire of sovereignty (for his daughter's son), to achieve the almost impossible, then said, 'O thou of virtuous soul, thou art come hither as full agent on behalf of thy father Santanu of immeasurable glory; be thou also the sole manager on my behalf in the matter of the bestowal of this my daughter. But, O amiable one, there is something else to be said, something else to be reflected upon by thee. O suppressor of foes, those that have daughters, from the very nature of their obligations, must say what I say. O thou that art devoted to truth, the promise thou hast given in the presence of these chiefs for the benefit of Satyavati, hath, indeed, been worthy of thee. O thou of mighty arms, I have not the least doubt of its ever being violated by thee. But I have my doubts in respect of the children thou mayst beget.'