Shiva Purana
शतकोटिमनुं जप्त्वा पंचोत्तरमतंद्रि तः । शिवलोकमवाप्नोति पंचमावरणाद्बहिः 1-17-११० ।
By chanting a hundred million (mantras) and remaining vigilant, one attains the Shiva Loka beyond the fifth veil.
english translation
zatakoTimanuM japtvA paMcottaramataMdri taH । zivalokamavApnoti paMcamAvaraNAdbahiH 1-17-110 ।
hk transliteration by Sanscript