Reference for Kelim 26:8
עוֹרוֹת בַּעַל הַבַּיִת, מַחֲשָׁבָה מְטַמֵּאתָן. וְשֶׁל עַבְּדָן, אֵין מַחֲשָׁבָה מְטַמֵּאתָן. וְשֶׁל גַּנָּב, מַחֲשָׁבָה מְטַמֵּאתָן. וְשֶׁל גַּזְלָן, אֵין מַחֲשָׁבָה מְטַמֵּאתָן. רַבִּי שִׁמְעוֹן אוֹמֵר, חִלּוּף הַדְּבָרִים, שֶׁל גַּזְלָן, מַחֲשָׁבָה מְטַמֵּאתָן. וְשֶׁל גַּנָּב, אֵין מַחֲשָׁבָה מְטַמֵּאתָן, מִפְּנֵי שֶׁלֹּא נִתְיָאֲשׁוּ הַבְּעָלִים:
The hides of a householder are rendered [susceptible to becoming] impure by intentional thought, but those of a tanner are not rendered [susceptible to becoming] impure by intentional thought. Those of a thief are rendered impure by intentional thought; but those of a robber are not rendered impure by intentional thought. Rabbi Shimon says: the matter should be reversed: those of a robber are rendered impure by intentional thought; but those of a thief are not rendered impure by intentional thought, since [in the latter case] the owners have not abandoned hope [for recovery].