68
Śrīmad-Bhāgavatam
[Canto 6, Ch. 8]
kara-nyāsam —the ritual known as  kara-nyāsa , which assigns the syllables of the  mantra  to the fingers;  tataḥ —thereafter;  kuryāt —should execute;  dvādaśa-akṣara —composed of twelve syllables;  vidyayā —with the  mantra ;  praṇava-ādi —beginning with the  oṁkāra ;  ya-kāra-antam —ending with the syllable  ya ;  aṅguli —on the fingers, beginning with the index finger;  aṅguṣṭha-parvasu —to the joints of the thumbs.
TRANSLATION
Then one should chant the  mantra  composed of twelve syllables [ oṁ namo bhagavate vāsudevāya ]. Preceding each syllable by the  oṁkāra , one should place the syllables of the  mantra  on the tips of his fingers, beginning with the index finger of the right hand and concluding with the index finger of the left. The four remaining syllables should be placed on the joints of the thumbs.
TEXTS 8-10
न्यसेद्धृदय ओङ्कारं विकारमनु मूर्धनि । 
    षकारं तु भ्रुवोर्मध्ये णकारं शिखया न्यसेत् ॥ ८ ॥ 
    वेकारं नेत्रयोर्युञ्ज्यान्नकारं सर्वसन्धिषु । 
    मकारमस्त्रयुद्धिश्य मन्त्रमूर्तिर्भवेद् बुधः ॥ ९ ॥ 
    सविसर्ग फडन्तं तत् सर्वदिक्षु विनिर्दिशेत् । 
    ॐ विष्णवे नम इति ॥ १० ॥
nyased dhṛdaya oṁkāraṁ 
    vi-kāram anu mūrdhani 
    ṣa-kāraṁ tu bhruvor madhye 
    ṇa-kāraṁ śikhayā nyaset
ve-kāraṁ netrayor yuñjyān 
    na-kāraṁ sarva-sandhiṣu 
    ma-kāram astram uddiśya 
    mantra-mūrtir bhaved budhaḥ
savisargaṁ phaḍ-antaṁ tat 
    sarva-dikṣu vinirdiśet 
    oṁ viṣṇave nama iti