SB 9.15.8

sa ṛṣiḥ prārthitaḥ patnyā
 śvaśrvā cāpatya-kāmyayā
śrapayitvobhayair mantraiś
 caruṁ snātuṁ gato muniḥ
saḥ — he (Ṛcīka); ṛṣiḥ — the great saint; prārthitaḥ — being requested; patnyā — by his wife; śvaśrvā — by his mother-in-law; ca — also; apatya-kāmyayā — desiring a son; śrapayitvā — after cooking; ubhayaiḥ — both; mantraiḥ — by chanting particular mantras; carum — a preparation for offering in a sacrifice; snātum — to bathe; gataḥ — went out; muniḥ — the great sage.
Thereafter, Ṛcīka Muni’s wife and mother-in-law, each desiring a son, requested the Muni to prepare an oblation. Thus Ṛcīka Muni prepared one oblation for his wife with a brāhmaṇa mantra and another for his mother-in-law with a kṣatriya mantra. Then he went out to bathe.