בְּעִדָּנָ֡א דִּֽי־תִשְׁמְע֡וּן קָ֣ל קַרְנָ֣א מַ֠שְׁרוֹקִיתָא קיתרוס [קַתְר֨וֹס] סַבְּכָ֤א פְּסַנְתֵּרִין֙ סוּמְפֹּ֣נְיָ֔ה וְכֹ֖ל זְנֵ֣י זְמָרָ֑א תִּפְּל֤וּן וְתִסְגְּדוּן֙ לְצֶ֣לֶם דַּהֲבָ֔א דִּ֥י הֲקֵ֖ים נְבוּכַדְנֶצַּ֥ר מַלְכָּֽא׃
너희는 나팔과 피리와 수금과 삼현금과 양금과 생황과 및 모든 악기 소리를 들을 때에 엎드리어 느부갓네살 왕의 세운 금신상에게 절하라
Sefer Daniel; Opportunity in Exile
Abarbanel understands “Idan” as referring to 410 years, the number of years Bayit Rishon stood. He believes that “Idan, Idanin, UFelag Idan” refers to 3.5 “Idans” = 1435 years. The starting point is 70 C.E., the year of Churban Bayit Sheini. Result – the Keitz is 1505 C.E.
Sefer Daniel; Opportunity in Exile
The advantage to Ibn Ezra is that his hair and nails grow longer in years rather than months. According to the American Academy of Dermatology, head hair grows at a rate of 3.5 inches in 7 months, and 42 inches in 7 years. By that point, continued hair growth would be supernatural, since human head hair grows in a maximum range of 12-42 inches, supporting Ibn Ezra. However, eagles don't grow feathers this long (10-22 in). Maybe we should be less literal, then. On the other hand, it's possible that by the fashion standards of 570 BCE Babylon, a hair length of 3.5 inches longer than normal (and seven months of untrimmed nails) was unheard of (at the very least, for a man), disgusting, unhuman, etc. This is particularly true of a king, who grooms to the highest standards, especially if Nevuchadnetzar took a haircut every day like Jewish kings. This would support Rav Saadia Gaon. Ibn Ezra’s main proof is the difficulty in returning to power after seven years of not ruling. However, there is a Midrash in the beginning of Kohelet that says Shlomo lost power, but it is not clear for how long. In any case, Shlomo is different because the Jews were peaceful, cohesive and loved their king; whereas the brutal Babylonian environment would lead to many coups, murders and fractures, etc.