Shiva Purana
ग्रामण्यश्च तथा यक्षा राक्षसाश्चासुरास्तथा ॥ सप्तसप्तगणाश्चैते सप्तच्छंदोमया हयाः ॥ १०७ ॥
There were also villagers yakshas rakshasas and asuras These seven horses are composed of seven chants.
english translation
grAmaNyazca tathA yakSA rAkSasAzcAsurAstathA ॥ saptasaptagaNAzcaite saptacchaMdomayA hayAH ॥ 107 ॥
hk transliteration by Sanscript