Ramayana
राक्षसेन्द्रः स तु तदा विचरन्वै महीतलम् । तदापश्यत्स गच्छन्तं पुष्पकेण धनेश्वरम् ॥ 7-9-3 ॥
That lord of the Rakshasas, while wandering over the surface of the earth, then beheld the lord of wealth (Kubera) traveling by the Pushpaka chariot.
english translation