Shiva Purana
न्यूनं चेत्फलमल्पं स्यादधिकं नैव दूष्यते । कर्तुरेकांगुलन्यूनं चरेपि च तथैव हि ९ ।
If it is shorter it is less efficacious; if it is longer there is no harm. A shortage by the breadth of the finger of the devotee in regard to the mobile one is similarly harmless.
english translation
nyUnaM cetphalamalpaM syAdadhikaM naiva dUSyate । karturekAMgulanyUnaM carepi ca tathaiva hi 9 ।
hk transliteration by Sanscript