Garudapurana 1.42.20

1.42.20

ātmatattvātmakaṃ paścāddevakākhyaṃ tator'cayet /
oṃ hauṃ hauṃ śivatattvāya namaḥ /
oṃ hīṃ(hīḥ) vidyātattvāya namaḥ //

then that consisting of the Ātman principle, and after that he should worship the one called the god: / “Oṃ hauṃ hauṃ, homage to the Śiva principle! / Oṃ hīṃ, homage to the Vidyā principle!