Shiva Purana
अथवाक्षरलक्षं वा ज्ञेयं शिवपदप्रदम् । सहस्रं तु सहस्राणां सहस्रेण दिनेन हि ४५ ।
Alternatively, one should understand that the repetition of a lakh (100,000) of letters (syllables) leads to the attainment of Shiva's supreme path, But a thousand repetitions of a thousand mantras, done over a thousand days, is even more powerful.
english translation
athavAkSaralakSaM vA jJeyaM zivapadapradam । sahasraM tu sahasrANAM sahasreNa dinena hi 45 ।
hk transliteration by Sanscript