Skandapurana 6.3.230.15

6.3.230.15

saṃhāralakṣaṇaṃ tadvadoṅkārasya ca sambhavaḥ .
tathaivauṃkāramāhātmyamamarakaṇṭakīrtanam .. 230.15 ..

likewise the nature of dissolution, and the origin of Oṅkāra, / as well as the māhātmya of Oṅkāra, and the celebration of Amarakaṇṭa;