Mishnayos Shabbos Perek 13 Mishnah 4

המלבן – [he bleaches] the wool and hatchels/beats it, and/or dyes it and/or spins it – for all of them are primary categories of [forbidden] labor [on the Sabbath]; their required quantity is in order that he spin from that wool a thread whose length is as far as the width of double size of a "סיט" (between the tip of the thumb and that of the index finger when held apart OR between thee root of the thumb and the tip of the index finger, when the former is leaning against the latter – see Talmud Shabbat 106a). And the "סיט" is according to the interruption that exists between the thumb to the finger – all that a person is able to widen it – and the measurement of this width is doubled – this is the double "סיט" -and the width between the thumb and the finger once – is also as far as the distance of a double "סיט" because it has double like that which is between the thumb and the [index] finger.

האורג שני חוטין – their measure/quantity is the width of the clothing as far as the "סיט" for even though he had not woven over the face of the entire width of the clothing, he is liable [for a sin-offering].