Ramayana
प्रवृत्तमादितः पूर्वसर्गं नारददर्शितम् । ततः प्रभृति सर्गांश्च यावद्विंशत्यगायताम् ॥ 7-94-16 ॥
They began from the very beginning with the first canto as shown by Narada, and from there onward they sang the cantos up to the twentieth.
english translation