Ramayana
अथवा पुष्पकमिदं धनदान्नान्यवाहनम् । अतो निष्पन्दमभवद्धनाध्यक्षविनाकृतम् ॥ 7-16-7 ॥
Or else this Pushpaka is the vehicle of none other than the Giver of Wealth, Kubera; therefore, being parted from the Lord of Riches, it has become motionless."
english translation