Shiva Purana
लक्षद्वादशयुक्तस्तु पूर्णब्राह्मण ईरितः । गायत्र्! या लक्षहीनं तु वेदकार्येन योजयेत् ४६ ।
A brahmin who has completed one million two hundred thousand repetitions becomes a full-fledged brahmin. A brahmin who has not completed at least a hundred thousand repetitions of Gāyatrī is not authorised in Vedic rites.
english translation
lakSadvAdazayuktastu pUrNabrAhmaNa IritaH । gAyatr! yA lakSahInaM tu vedakAryena yojayet 46 ।
hk transliteration by Sanscript