Vijnana Bhairava Tantra
पिण्डमन्त्रस्य सर्वस्य स्थूलवर्णक्रमेण तु । अर्धेन्दुबिन्दुनादान्तः शून्योच्चाराद्भवेच्छिवः ॥ ४२ ॥
By repetition of all the gross letters of the bija mantras successively, including the 'M', (and meditating thus! on the void within each sound, one verily becomes Shiva.
english translation
piNDamantrasya sarvasya sthUlavarNakrameNa tu । ardhendubindunAdAntaH zUnyoccArAdbhavecchivaH ॥ 42 ॥
hk transliteration by Sanscript