Shiva Purana
सप्तकोटि महामंत्राः पंचाक्षरपुरस्सराः । तथान्ये कोटिशो मंत्राः शैवकैवल्यहेतवः ६४ ।
The five-syllabled mantra which grants Śiva Kaivalya is on a par with seven crores of great and many crores of other mantras.
english translation
saptakoTi mahAmaMtrAH paMcAkSarapurassarAH । tathAnye koTizo maMtrAH zaivakaivalyahetavaH 64 ।
hk transliteration by Sanscript