Brahma Sutras
ॐ स्मर्यतेऽपि च लोके ॐ ॥ ३-१-१९॥
Moreover, there are records in the Smritis (of birth without parentage) as also in the Mahabharata etc., and there is popular belief as well.
english translation
OM smaryate'pi ca loke OM ॥ 3-1-19॥
hk transliteration by Sanscript