SB 6.19.1
sri-rajovaca
vratam pumsavanam brahman
bhavata yad udiritam
tasya veditum icchami
yena visnuh prasidati
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Maharaja Pariksit said: My dear lord, you have already spoken about the pumsavana vow. Now I want to hear about it in detail, for I understand that by observing this vow one can please the Supreme Lord, Visnu.