Shiva Purana
गुरूपदेशाज्जाप्यं वै ब्राह्मणानां नमोऽतकम् । पंचाक्षरं पंचलक्षमायुष्यं प्रजपेद्विधिः १२२ ।
Brahmin women must take instruction from a preceptor and perform the Japa with Namaḥ at the end. They shall repeat the five-syllabled mantra five hundred thousand times for their longevity. That is the rule.
english translation
gurUpadezAjjApyaM vai brAhmaNAnAM namo'takam । paMcAkSaraM paMcalakSamAyuSyaM prajapedvidhiH 122 ।
hk transliteration by Sanscript