Garudapurana 1.34.6

1.34.6

oṃ kārayuktā devasya śikhā jñeyā vṛṣadhvaja /
oṃ kṣaiṃ kavacāya huṃ vai kavacaṃ parikīrtitam //

Endowed with the syllable Oṃ, it is known as the tuft of hair of the god, O you whose banner bears a bull; / ‘Oṃ kṣaiṃ to the armor, huṃ’—the armor is proclaimed;