Skandapurana 6.3.159.85

6.3.159.85

dhenuke tvaṃ pratīkṣasva yamadvāre mahābhaye .
uttitīrṣurahaṃ dheno vaitaraṇyai namo'stu te .
ityanuvrajamantraḥ .. 159.85 ..

"O cow, wait for me at the terrifying door of Yama; / wishing to cross over, O cow, homage be to you, O Vaitaraṇī!" / Such is the mantra for following after.