In truth, during Talmudic times, the value of a given coin did not depend on the condition of the coin, rather on the amount that the metal in the coin was worth. Nevertheless, many people were concerned that the coin should be in good condition and that the minted form on the coin be sharp and clear, since then its value would be obvious to all. From a legal perspective, a zuz that was battered was really worth a zuz, but it was still difficult to get someone to accept it as payment.
The Gemara on yesterday’s daf (=page) closed with a Mishnah from Bava Kamma (daf 90a) that rules that ha-toke’a la-havero noten lo sela – that if someone boxes his friend, and he remains uninjured, he is obligated to pay him a sela because of the embarrassment that he caused.
The Gemara continues with a vignette that illustrates this law.
Hanan Bisha – the ruffian Hanan – boxed a man’s ear.He was brought before Rav Huna. The latter said to him: Give him half a zuz as compensation. Hanan possessed a zuza makha – a battered zuz – which could not be passed.He wanted to give him half a zuz from it. The other had no change. So he gave him another box on the ear and handed to him the whole zuz.
Many people will refuse to accept a battered coin, even if remains acceptable currency according to the law. The Rashbain Bava Kamma (daf 37a) explains that if there is no need to give change, it must be accepted as legal tender, which is why ultimately Hanan Bisha was able to pay using that coin. The Hagahot ha-Bah suggests that the injured party felt that he would not be able to use the coin, which is why he refused to accept it initially and be forced to give him change from it.