Shiva Purana
ततो विद्यामये तस्मिन्देहे दीपशिखाकृतिम् ॥ शिवान्निर्गतमात्मानं ब्रह्मरंध्रेण योजयेत् ॥ १४ ॥
In the body consisting of Vidyā, he shall join the Ātman that has come out of Śiva in the form of the flame of a lamp. He shall join it through the Brahmarandhra.
english translation
tato vidyAmaye tasmindehe dIpazikhAkRtim ॥ zivAnnirgatamAtmAnaM brahmaraMdhreNa yojayet ॥ 14 ॥
hk transliteration by Sanscript