Valmiki Ramayana Bala Kanda Sarga 45 Shloka 17
Original Shlokaतेषां चिन्तयतां राम बुद्धिरासीन्महात्मनाम्। क्षीरोदमथनं कृत्वा रसं प्राप्स्याम तत्र वै।।1.45.17।।
1 source checked for this shloka
राम O Rama, चिन्तयताम् while they were reflecting over this matter, तेषाम् for them, महात्मनाम् noble ones, बुद्धि: a thought, आसीत् came, क्षीरोदमथनम् churning the ocean of milk, कृत्वा having made, तत्र from there, रसम् nectar of immortality, प्राप्स्याम we will obtain.
"O Rama While the noble sons were reflecting over this matter an idea flashed across their minds to get nectar by churning the ocean of milk.