Ramayana
अरणिं तत्र निक्षिप्य मथनं चक्रुरोजसा । मन्त्रहोमैर्महात्मानः पुत्रहेतोर्निमेस्तदा ॥ 7-57-18 ॥
Placing the fire-kindling stick there, those great-souled ones then performed the churning with vigor, with sacred chants and oblations, for the sake of a son for Nimi.
english translation