Mahabharata 3.81.9

तत्र स्नात्वार्चयित्वा च त्रिलोकप्रभवं हरिम्अश्वमेधमवाप्नोति विष्णुलोकं च गच्छति

tatra snātvārcayitvā ca trilokaprabhavaṃ harimaśvamedhamavāpnoti viṣṇulokaṃ ca gacchati

Our plain-language meaning of this verse is waiting for scholar review.