Question: What is the source of the legend that during the Second Temple era the Jews promised Alexander the Great (356-323 B.C.E.) that they would name their children after him?
Answer: The earliest source for this legend that I could locate is the work Sefer Yosipon. According to Encyclopedia Judaica [2007 ed., v.11, p.461-462] Sefer Yosipon (also known as Josippon) is an anonymous history of the Second Temple era that was composed in Hebrew during the 10th century in southern Italy. During the Middle Ages the work was mistakenly ascribed to the Jewish historian Josephus Flavius (c.37 – after 100 C.E.) and became known as Yosipon (a Jewish-Greek form of Josephus). In the scholarly edition of Sefer Yosipon edited by David Flusser [Yerushalayim, Mosad Byalik, 1978-1980] the story is found in v.1, p.56-57, lines 37-45. Alexander is visiting the Temple in Jerusalem. After proclaiming his belief in the God of the Jews, Alexander asks the Jewish High Priest to create a memorial for Alexander in the Temple. Alexander will donate gold which will be crafted into a statue in his likeness. The statue will remain in the Temple to honor Alexander. The High Priest replied that it was forbidden to maintain a statue in the Temple but that Alexander’s memory would not be forgotten. All the priestly children born that year in Judea and Jerusalem would be named Alexander. Eventually, these children would serve in the Temple, thereby providing a memorial for Alexander. Flusser comments (ibid., p.56, note to line 41) that a similar story was recorded by the German poet Rudolf von Ems (c.1200-1254) in his work Alexanderroman. In von Ems’ version no mention is made of Alexander requesting a statue. Out of gratitude to Alexander’s kindness to them, the Jews spontaneously make the offer that henceforth one member of the Levitical house will always bear the name Alexander. Flusser thinks it likely that in recording their slightly different versions of the legend, both Yosipon and von Ems were drawing on a shared source that is at present lost to us.