Shiva Purana
सत्रमांगिरसा विप्राः कुर्वंत्यद्य सुमेधसः ॥ तत्र कर्मणि मुह्यन्ति षष्ठं षष्ठमहः प्रति ॥ १८॥
The intelligent Āṅgirasa. brahmins are performing a sacrifice. Every sixth day the rites are marred.
english translation
satramAMgirasA viprAH kurvaMtyadya sumedhasaH ॥ tatra karmaNi muhyanti SaSThaM SaSThamahaH prati ॥ 18॥
hk transliteration by Sanscript