Mbh 1.211.2b

And beholding the severity of their austerities, the celestials became alarmed. The gods began to cause numerous obstructions to impede the progress of their asceticism. The celestials repeatedly tempted the brothers by means of every precious possession and the most beautiful girls. The brothers broke not their vows. Then the celestials once more manifested, before the illustrious brothers, their powers of illusion. For it seemed their sisters, mothers, wives, and other relatives, with disordered hair and ornaments and robes, were running towards them in terror, pursued and struck by a Rakshasa with a lance in hand. And it seemed that the women implored the help of the brothers crying, ‘O save us!’ But all this went for nothing, for firmly wedded thereto, the brothers did not still break their vows. And when it was found that all this produced not the slightest impression on any of the two, both the women and the Rakshasa vanished from sight. At last the Grandsire himself, the Supreme Lord ever seeking the welfare of all, came unto those great Asuras and asked them to solicit the boon they desired. Then the brothers Sunda and Upasunda, both of great prowess, beholding the Grandsire, rose from their seats and waited with joined palms. And the brothers both said unto the God, ‘O Grandsire, if thou hast been pleased with these our ascetic austerities, and art, O lord, propitious unto us, then let us have knowledge of all weapons and of all powers of illusion. Let us be endued with great strength, and let us be able to assume any form at will. And last of all, let us also be immortal.’ Hearing these words of theirs, Brahman said, ‘Except the immortality you ask for, you shall be given all that you desire. Solicit you some form of death by which you may still be equal unto the immortals. And since you have undergone these severe ascetic austerities from desire of sovereignty alone I cannot confer on you the boon of immortality.