בִּשְׁנַ֣ת שָׁל֔וֹשׁ לְמַלְכ֖וּת בֵּלְאשַׁצַּ֣ר הַמֶּ֑לֶךְ חָז֞וֹן נִרְאָ֤ה אֵלַי֙ אֲנִ֣י דָנִיֵּ֔אל אַחֲרֵ֛י הַנִּרְאָ֥ה אֵלַ֖י בַּתְּחִלָּֽה׃
In the third year of the reign of king Belshazzar a vision appeared unto me, even unto me Daniel, after that which appeared unto me at the first.
Rashi
And two of his: As we find that Balshazzar reigned three years. As it is written in the book of Daniel (8:1), "In the third year of the reign of King Belshazzar, a vision appeared to me, to me, Daniel, etc."