Manusmriti

siva.sh/manusmriti/2/76

अकारं चाप्युकारं च मकारं च प्रजापतिः । वेदत्रयान्निरदुहद् भूर्भुवः स्वरितीति च ॥ ७६ ॥

sanskrit

Pragapati (the lord of creatures) milked out (as it were) from the three Vedas the sounds A, U, and M, and (the Vyahritis) Bhuh, Bhuvah, Svah.

english translation

akAraM cApyukAraM ca makAraM ca prajApatiH | vedatrayAnniraduhad bhUrbhuvaH svaritIti ca || 76 ||

hk transliteration by Sanscript