Reference for Shabbat 20:3
אֵין שׁוֹרִין אֶת הַחִלְתִּית בְּפוֹשְׁרִין, אֲבָל נוֹתֵן לְתוֹךְ הַחֹמֶץ. וְאֵין שׁוֹרִין אֶת הַכַּרְשִׁינִין וְלֹא שָׁפִין אוֹתָן, אֲבָל נוֹתֵן לְתוֹךְ הַכְּבָרָה אוֹ לְתוֹךְ הַכַּלְכַּלָּה. אֵין כּוֹבְרִין אֶת הַתֶּבֶן בִּכְבָרָה, וְלֹא יִתְּנֶנּוּ עַל גַּבֵּי מָקוֹם גָּבוֹהַּ בִּשְׁבִיל שֶׁיֵּרֵד הַמֹּץ, אֲבָל נוֹטֵל הוּא בִכְבָרָה וְנוֹתֵן לְתוֹךְ הָאֵבוּס:
It is not permitted to soak chiltith (asafetida) in lukewarm water. [Chiltith is hot and commonly eaten in cold places. It is not permitted to soak it on Shabbath because it gives the appearance of a mundane activity.]; but it is permitted to put it in vinegar. And it is not permitted to soak horse-beans [in a vessel to separate their psoleth (unwanted matter), which floats to the top], and it is not permitted to rub them [with one's hands so that the psoleth falls, this being borer.] But it is permitted to place them into a sieve or into a (perforated) basket, [even though the psoleth sometimes falls through the holes and is sieved of itself.] It is not permitted to sieve hay in a sieve [They would make hay from straw by cutting it with threshing sledges, the tails of the stalks becoming hay], and it may not be placed on a height so that the chaff descend. [The chaff is not suitable for animal food, and they would generally sieve the hay to extract it.] But he may place it (the hay) on a sieve or into the manger, [even if the chaff fall of itself; for "something which is not intended is permitted," as per R. Shimon.]