Shabbos13: 2
הָעוֹשֶׂה שְׁנֵי בָתֵּי נִירִין בְּנִירִין, בְּקֵירוֹס; בְּנָפָה, בִּכְבָרָה, וּבְסַל, חַיָּב. וְהַתּוֹפֵר שְׁתֵּי תְפִירוֹת, וְהַקּוֹרֵעַ עַל מְנָת לִתְפֹּר שְׁתֵּי תְפִירוֹת.
One who sets two heddles of a home loom, [or] of a commercial loom; [and one who positions the warp reeds of] a sifter, a sieve, or a basket, is liable. One who sews two stitches, and one who tears in order to sew two stitches.
Shabbos13: 3
הַקּוֹרֵעַ בַּחֲמָתוֹ, וְעַל מֵתוֹ, וְכָל הַמְקַלְקְלִין, פְּטוּרִין. וְהַמְקַלְקֵל עַל־מְנָת לְתַקֵּן, שִׁעוּרוֹ כִמְתַקֵּן.
One who tears in his anger, or for his dead, and all who act destructively, are exempt. But one who destroys in order to repair, his [minimum] measure [for liability] is the same as for repairs.