Canto 2 -
Ayodhyā-kāṇḍa
Chapter 50: The Meeting of Rāma and Guha
Text 2.50.44
कुशचीराजिनधरं फलमूलाशिनं च माम्।
विद्धि प्रणिहितं धर्मे तापसं वनगोचरम्॥
kuśa-cīrājinadharaṁ phala-mūlāśinaṁ ca mām
viddhi praṇihitaṁ dharme tāpasaṁ vana-gocaram
kuśa-cīra-ajinadharam = to be wearing kuśa, bark and deer skin; phala-mūla-aśinam ca = eating fruits and roots; mām = Me; viddhi = know; praṇihitam = I am attentive; dharme = to dharma; tāpasam = and I am an ascetic; vana-gocaram = living within a forest.
Know Me to be wearing kuśa, bark and deer skin, eating fruits and roots. I am attentive to dharma and I am an ascetic living within a forest.
Here Śrī Vālmīki presents the reason for Rāma not accepting the kingdom, food and other items [presented by Guha].
Rāma wore kuśa grass as a pavitra, belt and so on. He wore a cloth made from bark and used the skin of black deer. Dharma here refers to carrying out the order of His father and so on.