Mbh 3.147.1b

Then that foremost of kings, Rama was established in the kingdom. Thereafter, I asked a boon of the lotus-eyed Rama, saying, ‘O slayer of foes, Rama, may I live as long as the history of thy deeds remaineth extant on earth!” Thereupon he said, ‘So be it. O represser of foes, O Bhima, through the grace of Sita also, here all excellent objects of entertainment are supplied to me, whoever abide at this place. Rama reigned for the thousand and ten hundred years. Then he ascended to his own abode. Ever since, here Apsaras and Gandharvas delight me, singing for aye the deeds of that hero, O sinless one. O son of the Kurus, this path is impassable to mortals. For this, O Bharata, as also with the view that none might defeat or curse thee, have I obstructed thy passage to this path trod by the immortals. This is one of the paths to heaven, for the celestials; mortals cannot pass this way. But the lake in search of which thou hast come, lieth even in that direction.”