SB 6.19.1

śrī-rājovāca
vrataṁ puṁsavanaṁ brahman
 bhavatā yad udīritam
tasya veditum icchāmi
 yena viṣṇuḥ prasīdati
Word for word: 
śrī-rājā uvāca — Mahārāja Parīkṣit said; vratam — the vow; puṁsavanam — called puṁsavana; brahman — O brāhmaṇa; bhavatā — by you; yat — which; udīritam — was spoken of; tasya — of that; veditum — to know; icchāmi — I want; yena — by which; viṣṇuḥ — Lord Viṣṇu; prasīdati — is pleased.
Translation: 
Mahārāja Parīkṣit said: My dear lord, you have already spoken about the puṁsavana vow. Now I want to hear about it in detail, for I understand that by observing this vow one can please the Supreme Lord, Viṣṇu.