Srimad Bhagavatam Canto 09, Chapter 18, Text 37

SB 9.18.37

sri-yayatir uvaca
atrpto ’smy adya kamanam
 brahman duhitari sma te
vyatyasyatam yatha-kamam
 vayasa yo ’bhidhasyati
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
King Yayati said, “O learned, worshipable brahmana, I have not yet satisfied my lusty desires with your daughter.” Sukracarya then replied, “You may exchange your old age with someone who will agree to transfer his youth to you.”
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
When King Yayati said that he had not yet satisfied his lusty desires with Sukracarya’s daughter, Sukracarya saw that it was against the interests of his own daughter for Yayati to continue in old age and invalidity, for certainly his lusty daughter would not be satisfied. Therefore Sukracarya blessed his son-in-law by saying that he could exchange his old age for someone else’s youth. He indicated that if Yayati’s son would exchange his youth for Yayati’s old age, Yayati could continue to enjoy sex with Devayani.