Valmiki Ramayana Ayodhya Kanda Sarga 55 Shloka 18

वीरौ heroes, तौ those two, दशरथात्मजौ Dasratha's sons, सङ्घाटम् that float, प्रतिगृह्य tightly holding, प्रथमम् at first, सीताम् Sita, आरोप्य making her board, ततः then, यत्तौ carefully, प्रतेरतुः crossed.

Those valiant sons of Dasaratha held the float (firmly) to help Sita step on to it. Then they crossed the river carefully.