Mishná sur Kéilim 17:20

Bikkurim are brought only from the seven species. Not from dates grown on hills, nor from [the other species] grown in the valley, nor from olives that are not choice. Bikkurim are not to be brought before Shavuot. The people from Mt. Zevoim brought bikkurim prior to Atzeret (Shavuot), but they did not accept from them, on for it is written in the Torah: “And the festival of the harvest, the first-fruits of your labors, which you have sown in the field” (Exodus 23:16).

The following defile by contact and carriage but not by overshadowing: A bone of barleycorn size, Earth from a foreign country, A bet peras, A limb of a corpse, or a limb [severed] from a living person which has no longer its appropriate flesh, A spine or a skull which is deficient. How much is [considered] a deficiency in the spine? Bet Shammai say: two vertebrae, But Bet Hillel say: even one vertebra. And in the skull? Bet Shammai say: [the size of a] hole [made] by a drill, But Bet Hillel say: as much as would be taken from a living person and he would die. Of what drill did they speak? Of the small one [used] by physicians, the words of Rabbi Meir. But the sages say: of the large one in the Temple-chamber.

[An object] one handbreadth square and one handbreadth high conveys uncleanness and blocks uncleanness. How does it [block uncleanness]? In the case of a covered drain beneath a house, if it has a space a handbreadth wide and its outlet was a handbreadth wide, and there is uncleanness inside it, the house remains clean; And when there is uncleanness in the house, that which is within [the drain] remains clean, for the manner of the uncleanness is to go out and not to go in. If it had a space one handbreadth wide but its outlet was not one handbreadth wide, when there is uncleanness in it, the house becomes unclean; But when there is uncleanness in the house, that which is within it remains clean, for the manner of the uncleanness is to go out and not to go in. If it did not have a space one handbreadth wide and its outlet was not one handbreadth wide, when there is uncleanness within it, the house becomes unclean; And when there is uncleanness in the house, it [also] becomes unclean. It makes no difference if the cavity was carved out by water or by a sheretz or if it had been eaten out by salt. And similarly [if it is in] a row of stones or a pile of beams. Rabbi Judah says: any "tent" not made by a person is not considered a tent’. But he agrees that crevices and crags [can be considered as ‘tents’].

One who makes a new light hole, its minimum size is that of a hole made by the large drill of the Temple chamber. The remains of a light-hole [the size is] two fingerbreadths high by a thumb-breadth broad. The following is considered the remains of a light-hole: a window that a person had blocked up but had not been able to finish [being blocked up]. [A hole] that was bored by water, or by reptiles or eaten away by salt: the minimum size is that of a fist. If he intended to use it, its minimum size is one handbreadth square; For lighting its minimum size is that of a hole made by the drill. The holes in grating or lattice-work may be joined together to form [an opening] the size of a hole made by the drill, according to the opinion of Bet Shammai. Bet Hillel says: unless there is a hole of the size made by the drill in one place. [The above applies] for purposes of allowing the uncleanness to come in or to go out. Rabbi Shimon says: only for allowing the uncleanness to come in; but for allowing the uncleanness to go out [the minimum size] is one handbreadth square.

The following [objects serve to] reduce [the area of a square] handbreadth:[A portion] of less than an olive-size of flesh [of a corpse] reduces [the opening for uncleanness that is] caused by a quarter of a kav of bones [from a corpse]; [A portion] of less than a barley-corn size of bone reduces [the opening for uncleanness that is] caused by an olive-sized portion of flesh; Less than an olive-sized portion of a corpse, Less than an olive-sized portion of carrion, Less than a lentil-sized portion of sheretz; Less than an egg-sized portion of food; Produce growing next to the window, A cobweb having substance; The carcass of a clean bird that he did not intend to eat, And the carcass of an unclean bird that had been intended [for food] that had not been rendered susceptible [to uncleanness], or which had been rendered susceptible [to uncleanness] but had not been intended [for food].