Canto 2 -
Ayodhyā-kāṇḍa
Chapter 77: Bharata and Śatrughna Lament About Daśaratha’s Departure
Text 2.77.8

दृष्ट्वा भस्मारुणं तच्च दग्धास्थिस्थानमण्डलम्।
पितुः शरीरनिर्वाणं निष्टनन्विषसाद सः॥

dṛṣṭvā bhasmāruṇaṁ tac ca dagdhāsthi-sthāna-maṇḍalam
pituḥ śarīra-nirvāṇaṁ niṣṭanan viṣasāda saḥ

dṛṣṭvā = seeing; bhasma-aruṇam = and red ashes; tat ca = the; dagdha-asthi-sthāna-maṇḍalam = place of his burnt bones; pituḥ = His father’s; śarīra-nirvāṇam = the spot where body had been destroyed 5; niṣṭanan = cried loudly and; viṣasāda = became dejected; saḥ = He.

Seeing the spot where His father’s body had been destroyed, the place of his burnt bones and red ashes, He cried loudly and became dejected.

The ashes were red because the bones had been burnt too much.