מִמְּךָ

From you

Concerning a promissory note in which it is written: I, so-and-so, borrowed one hundred dinars from you, anyone who claims to be the creditor and is in possession of such a document can collect the stated debt with it. This is the halakha provided that the holder of the promissory note claims to be the creditor; otherwise it is unreasonable to assume that a debtor would obligate himself to anyone who might happen to be holding the document (Shakh; Netivot HaMishpat). The concern that perhaps the true creditor lost the note and the current holder found it is not taken into consideration, in accordance with Rabba’s statement. This applies only if the note is signed by witnesses. If it was written or signed by the debtor himself, since he has the right to claim that the debt has been repaid, he also is deemed credible if he claims: I borrowed the money from someone else, who apparently lost the note, and you found it. He would then be exempt from repaying the debt (Rambam Sefer Mishpatim, Hilkhot Malve VeLoveh 24:9; Shulḥan Arukh, Ḥoshen Mishpat 50:1, and in the comment of Rema; 61:10).

רֵישׁ גָּלוּתָא

Exilarch

The person who filled the position of Exilarch, who was descended from the kings of the house of David, was recognized by the Jews as the heir to the scepter of Judah (see Genesis 49:10) and entrusted with broad official powers. He was the leader of the Jews of the Persian Empire and their representative to the authorities, who regarded him as a member of a royal dynasty. Consequently, the Exilarch enjoyed a lofty position within the Persian court.

שָׁבוֹר מַלְכָּא

King Shapur

This refers to the Persian king Shapur I, 241–272 CE, the second ruler of the Sassanid dynasty. He was one of the great Persian kings who expanded the borders of the kingdom. He waged several wars against the Romans and conquered extensive territory from them, reaching as far as Syria. He even managed to take the Roman Emperor Valerianus captive. Despite this, he did not always win his wars, and was defeated by the Romans in several battles. Unlike most of the kings of that dynasty, King Shapur I was tolerant of other religions. The Gemara relates at length his close relationship with the Jews, and how he valued and appreciated Jewish customs. On several occasions the Talmud recounts his friendship with the amora Shmuel.