Agnipurana 85.13

85.13

sahaitena ca paryantāḥ kathyante 'tha padānyapi /
vyāpin oṃ arūpa oṃ pramatha oṃ tejaḥ oṃ jyotiḥ oṃ puruṣa
oṃ agne oṃ adhūma oṃ abhasma oṃ anādi oṃ nānā oṃ dhūdhū
oṃ bhūḥ oṃ bhuvaḥ oṃ svaḥ anidhana nidhanodbhava śiva śarva
paramātman maheśvara mahādeva sadbhāveśvara mahātejaḥ
yogādhipataye muñca prathama sarva sarvesarveti dvātriṃśat padāni
vījabhāve trayo mantrā vāmadevaḥ śivaḥ śikhā //

these, ending with this one, are mentioned. Now also the words:
'vyāpin oṃ, arūpa oṃ, pramatha oṃ, tejaḥ oṃ, jyotiḥ oṃ, puruṣa oṃ, agne oṃ, adhūma oṃ, abhasma oṃ, anādi oṃ, nānā oṃ, dhūdhū oṃ, bhūḥ oṃ, bhuvaḥ oṃ, svaḥ, anidhana, nidhanodbhava, śiva, śarva, paramātman, maheśvara, mahādeva, sadbhāveśvara, mahātejaḥ, yogādhipataye muñca prathama sarva sarvesarva'—thus are the thirty-two words.
When in the form of seed-syllables, there are three mantras: Vāmadeva, Śiva, and Śikhā.