Mishnah Shabbat 7:1-2; ch. 12

(1) They [the Sages] stated a major rule with respect to Shabbat: [If] one [entirely] forgot it was Shabbat, and performed many Melakhot [constructive activities forbidden on Shabbat and festivals] on many Shabbatot, he is only liable for one Chattat [an offering brought to expiate sin]. [If] one was aware of/knew about [yodea] the principle of Shabbat, but performed many Melakhot on many Shabbatot he is liable for [one Chattat] for every Shabbat. [If] one knew [] it was Shabbat and performed many Melakhot on many Shabbatot, he is liable [to bring a separate a Chattat] for every principal Melakhah. [If] one performed many Melakhot all of which stem from the same principal Melakhah, he is bound to bring but one Chattat.

(2) The [number of] principal Melakhot is forty minus one. [The forbidden Melakhot are]: Sowing, plowing, reaping, binding sheaves, threshing, winnowing, sorting, grinding, sifting, kneading, baking, shearing wool, whitening it, combing it, dyeing it, spinning, weaving, making two loops, weaving two threads, separating two threads, tying [a knot], untying [a knot], sewing two stitches, tearing for the purpose of sewing two stitches, hunting a deer, slaughtering it, skinning it, salting it, curing its hide, scraping it, cutting it, writing two letters, erasing for the purpose of writing two letters, building, demolishing, extinguishing a flame, lighting a flame, striking with a hammer, carrying from one domain to another. These are the principal Melakhot - [they number] forty minus one.

(1) [If] one builds, how much must he build to be liable? [If] one builds the smallest quantity [he is liable]. [If] one chops stone, or strikes with a hammer, or uses an adze, or bores a hole - [if any of these are done] in the smallest quantity, he is liable. This is the principle: If one performs a Melakhah [a constructive activity forbidden on Shabbat and festivals] and that Melakhah endures on the Shabbat, he is liable. Rabbi Shimon ben Gamliel says: One is [likewise liable if] he strikes a hammer on an anvil because it is like he improves the tool.

(2) [If] one plows the smallest quantity, or weeds, or cuts [off dried branches], or trims [fresh branches] he is liable for the smallest quantity. [If] one gathers branches to improve [the tree], he is liable for the smallest quantity; [if one gathers branches] to burn [as fuel, he is liable if he gathers] sufficient [wood] to boil a light egg. [If] one gathers herbs to improve [the ground], he is liable for the smallest quantity; [if one gathers grasses] for an animal [he is liable if he gathers] sufficient [grasses] for a kid's mouthful.

(3) [If] one writes two letters he is liable, regardless [if he does so] with his right hand or with his left hand, or whether [he writes] the same letter [twice] or two [different] letters, or [if he writes with] different inks. One is liable [for writing] in any language. Rabbi Yose says: They only forbade writing two letters because [they serve] as a sign, for they used to write on the Tabernacle boards to know which board went next to which. Rabbi says: We find short names [which are subsumed within] large names, like Shem within Shimon or Shemuel; Noach‎ within Nachor; Dan within Daniel; Gad‎ within Gadiel.

(4) [If] one writes two letters under one spell of unawareness, he is liable. He is liable if he writes in ink, or Sikra [an orange earth], or resin, or Kankantom [a copper based paint], or any substance that leaves a mark. [If one writes] on two [adjacent] walls [that form a] corner, or on two leaves of a tablet so that the [letters match up and] are read together, he is liable. [If] one writes on his flesh, he is liable. [If] one scratches [letters] on his flesh, Rabbi Eliezer deems him liable for a Chattat [an offering brought to expiate sin], but Rabbi Yehoshua exempts him.

(5) [If] one writes with a liquid, or with fruit juice, or in the dust of the road, or scribes' dust, or with any substance which does not endure, he is exempt. [If one writes] with the back of his hand [with one's hand turned over], or with his foot, or with his mouth, or with his elbow, he is exempt. [If] one writes one letter next to [existing] writing, or writes on top of writing, or [if] he intended to write [the letter] ‎Chet, but wrote two ‏Zayinin‎, [or wrote] one [letter] on the ground and one on the board [ceiling], or wrote on two [non-adjacent] walls of the house, or on two leaves of a tablet such that the [letters do not match up and] are not read together, he is exempt. [If] one writes a letter as an abbreviation, Rabbi Yehoshua ben Beteira deems him liable, but the Sages exempt him.

(6) [If] one writes two letters under two [separate] spells of unawareness, one in the morning and one in the evening, Rabban Gamaliel deems him liable, but the Sages exempt him.