Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 18: The Advent of Rāma, Lakṣmaṇa, Bharata and Śatrughna
Text 1.18.45

तं दृष्ट्वा ज्वलितं दीप्त्या तापसं संशितव्रतम्।
प्रहृष्टवदनो राजा ततोऽर्घ्यमुपहारयत्॥

taṁ dṛṣṭvā jvalitaṁ dīptyā tāpasaṁ saṁśita-vratam
prahṛṣṭa-vadano
rājā tato ’rghyam upahārayat

tam = the; dṛṣṭvā = seeing; jvalitam = dazzling; dīptyā = with illumination; tāpasam = ascetic; saṁśita-vratam = of sharp vows; prahṛṣṭa-vadanaḥ = with a delighted face; rājā = the king; tataḥ = then; arghyam = arghya; upahārayat = had Vasiṣṭha offer him.

Seeing the ascetic of sharp vows dazzling with illumination, the king, with a delighted face, then had Vasiṣṭha offer him arghya.

Arghya is water for worship.