Siman - Shabbos Daf 103

• Striking hammer on an anvil

In the Mishnah on 102b, Rabban Shimon ben Gamliel stated that one who strikes with a hammer on an anvil while working, is chayav, because he is like one who improves the work he is doing.

The Gemara seeks to understand what act he is doing that makes him liable, and brings Abaye and Rava who both say that banging a hammer on an anvil is considered a melacha, as that is what those who pounded the sheets of gold for the Mishkan did.

Rashi explains that after every three strikes on the sheet done to thin them, the smiths would strike once on an anvil to ensure the surface of the hammer remained smooth and would not puncture the sheets. He adds that coin manufacturers in his own locale did this.

• Chayav for writing with right or left hand

The second Mishnah on the Daf states that one who writes two letters with either his right or left hand, is chayav. The Gemara asks why one is chayav for writing with his left hand since it is not the normal manner for writing? Rebbe Yirmiya suggested that the Mishnah is referring to a left-handed person, but this is rejected because then he should not be liable for writing with his right hand.

• Abaye answers that the Mishnah is dealing with an ambidextrous person. The Ritva asks why then is this Mishnah not obvious? He explains that Abaye is referring to someone who favors one hand but is somewhat proficient with the other.

• Rav Yaakov the son of Yaakov’s daughter said the author of the Mishnah is Rebbe Yose who said that one who writes two letters is chayav because of making a roshem (marking). Since making mere marks can be done perfectly well with the left hand, it is the normal manner to also use one’s left hand, and therefore he is chayav.

• Writing short word instead of long one

In the same Mishnah regarding the melacha of kesiva (writing), Rebbe Yehuda states that we find a short word that is part of a long word, such as Shem from Shimon or Shmuel, Noach from Nachor, Dan from Daniel, and Gad from Gadiel. Rashi explains that Rebbe Yehuda is coming to teach that even though the writer did not complete the word he intended, he is chayav if the letters he wrote comprise a short word.

The Gemara asks how one could be chayav for writing Shem from Shimon, since the mem from Shem is closed (סתום) and the mem from Shimon is open (פתוח)? Rav Chisda says that this teaches that if a sofer wrote a closed letter as an open letter, it is valid.