Skandapurana 6.3.230.29

6.3.230.29

pitṛtīrthaṃ ca tatraiva oṅkārasya ca sambhavam .
māhātmyaṃ pañcaliṅgānāmoṅkārasya munīśvarāḥ .. 230.29 ..

And there itself is Pitṛtīrtha, and the origin of Oṅkāra, / and the māhātmya of the five liṅgas of Oṅkāra, O best of sages;