One who writes two letters in two periods of forgetfulness, one in the morning and one in the afternoon, Rabban Gamliel holds [him] liable. But the Sages exempt [him].

R’ Eliezer says: One who weaves three threads at the beginning, or [adds] one thread to woven fabric, is liable. But the Sages say: Whether at the beginning or at the end, its amount is two threads.