Shiva Purana
स्व शाखोक्तप्रकारेण पुरस्तात्तन्त्रकर्म्म च ॥ निर्वर्त्य सर्पिषा मिश्रं चरुम्प्राश्य पुरोधसे ॥ ४१ ॥
and the rituals of the tantra in the manner described in their own branches. After completing the offering mixed with butter and offered to the priest.
english translation
sva zAkhoktaprakAreNa purastAttantrakarmma ca ॥ nirvartya sarpiSA mizraM carumprAzya purodhase ॥ 41 ॥
hk transliteration by Sanscript