Ramayana
इन्द्रयज्ञावसाने तु वसिष्ठो भगवनृषिः । सकाशमागतो राज्ञो हौत्रं कर्तुमनिन्दितः ॥ 7-55-13 ॥
At the conclusion of Indra's sacrifice, the venerable and blameless sage Vasishtha came into the presence of the king to perform the office of the officiating priest.
english translation