Shiva Purana
वैरूप्यमतिरात्रं च पश्चिमादसृजन्मुखात् ॥ एकविंशमथर्वाणमाप्तोर्यामाणमेव च ॥ ६१ ॥
From the west he created a disfigurement and a nightmare. The twenty-first Atharva Veda and the Aptoryāma Veda are also mentioned.
english translation
vairUpyamatirAtraM ca pazcimAdasRjanmukhAt ॥ ekaviMzamatharvANamAptoryAmANameva ca ॥ 61 ॥
hk transliteration by Sanscript