Shiva Purana
मातृकामयमीशानम्पञ्चब्रह्ममयन्तथा॥ ॐकाराख्यमयं चैव हंसन्यासमयन्तथा ॥ ६२ ॥
The Lord who desires the mother and the five Brahmans. The omkara is also used for the placement of the swan.
english translation
mAtRkAmayamIzAnampaJcabrahmamayantathA॥ OMkArAkhyamayaM caiva haMsanyAsamayantathA ॥ 62 ॥
hk transliteration by Sanscript