Keilim29: 4
חוּט מֹאזְנַיִם שֶׁל זֶהָבִים וְשֶׁל שׁוֹקְלֵי אַרְגָּמָן טוֹב — שָׁלֹשׁ אֶצְבָּעוֹת. יַד הַקַּרְדֹּם מֵאַחֲרָיו — שָׁלֹשׁ אֶצְבָּעוֹת. רַבִּי יוֹסֵי אוֹמֵר: טֶפַח — טָהוֹר.
The cord of a goldsmith’s balance, and [that] of a weigher of good [-quality] purple [wool], [their measure is] three fingerbreadths. The handle of a hatchet from its back, [its measure is] three fingerbreadths. R’ Yose says: [If it is] one handbreadth, [it is] tahor.