Srimad Bhagavatam Canto 09, Chapter 20, Text 17

SB 9.20.17

amogha-viryo rajarsir
 mahisyam viryam adadhe
svo-bhute sva-puram yatah
 kalenasuta sa sutam
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
King Dusmanta, who never discharged semen without a result, placed his semen at night in the womb of his Queen, Sakuntala, and in the morning he returned to his palace. Thereafter, in due course of time, Sakuntala gave birth to a son.
Srimad Bhagavatam Canto 09, Chapter 20, Text 16
Srimad Bhagavatam Canto 09, Chapter 20, Text 18