SB 4.13.32
tatha sadhaya bhadram te
atmanam suprajam nrpa
istas te putra-kamasya
putram dasyati yajña-bhuk
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O King, we wish all good fortune for you. You have no son, but if you pray at once to the Supreme Lord and ask for a son, and if you execute the sacrifice for that purpose, the enjoyer of the sacrifice, the Supreme Personality of Godhead, will fulfill your desire.