Ramayana
न सीतायाः परां भार्यां वव्रे स रघुनन्दनः । यज्ञे यज्ञे च पत्न्यर्थं जानकी काञ्चनी भवत् ॥ 7-99-8 ॥
That delight of the Raghus took no other wife in place of Sita; and at each and every sacrifice a golden image of Janaki served in the wife's stead.
english translation