Valmiki Ramayana Ayodhya Kanda Sarga 20 Shloka 19

शुक्लक्षौमसंवीताम् wearing white silk, व्रतयोगेन due to observance of vows, कर्शिताम् emaciated, देववर्णिनीम् having divine complexion, अद्भिः with water, देवताम् to deities, तर्पयन्तीम् engaged in propitiating, ताम् her (Kausalya), ददर्श beheld.

Kausalya, emaciated due to observance of vows and clad in white silk looked like a celestial being. She was engaged in offering libations to the deities.