Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 2: Lord Brahmā Instructs Vālmīki
Text 1.2.36

यावत्स्थास्यन्ति गिरयः सरितश्च महीतले।
तावद्रामायणकथा लोकेषु प्रचरिष्यति॥

yāvat sthāsyanti girayaḥ saritaś ca mahītale
tāvad rāmāyaṇa-kathā lokeṣu pracariṣyati

yāvat = as long; sthāsyanti = there are; girayaḥ = mountains; saritaḥ ca = and rivers; mahī-tale = on the surface of the earth; tāvat = as; rāmāyaṇa-kathā = the narration of Rāmāyaṇa; lokeṣu = in the worlds; pracariṣyati = will be propagated.

As long as there are mountains and rivers on the surface of the earth, the narration of Rāmāyaṇa will be propagated in the worlds.

Another purpose to be achieved through the composition of this poem is fame. As long as Śrī Vālmīki’s work is propagated, he will be famous.