Shabbos 12:6

If a person writes two letters in two different states of unawareness, one in the morning and one in the evening, Rabban Gamaliel says that he is liable but the Sages say that he is exempt.

Shabbos 13:1

Rabbi Eliezer says that if a person weaves three threads at the beginning of the weaving process or one thread on the web of a loom (at the end of the process), he is liable. The Sages say that the quantity that makes one liable is two threads regardless of the point in the process.