Shiva Purana
कनिष्ठा क्षरिणी प्रोक्ता जपकर्मणि शोभना ॥ अंगुष्ठेन जपेज्जप्यमन्यैरंगुलिभिस्सह ॥ ४२ ॥
The use of little finger in the Japa shall be avoided. In the act ot Japa it is held to be auspicious. The Japa shall be performed by means of the thumb in contact with other fingers.
english translation
kaniSThA kSariNI proktA japakarmaNi zobhanA ॥ aMguSThena japejjapyamanyairaMgulibhissaha ॥ 42 ॥
hk transliteration by Sanscript