וַיְמַן֩ לָהֶ֨ם הַמֶּ֜לֶךְ דְּבַר־י֣וֹם בְּיוֹמ֗וֹ מִפַּת־בַּ֤ג הַמֶּ֙לֶךְ֙ וּמִיֵּ֣ין מִשְׁתָּ֔יו וּֽלְגַדְּלָ֖ם שָׁנִ֣ים שָׁל֑וֹשׁ וּמִ֨קְצָתָ֔ם יַֽעַמְד֖וּ לִפְנֵ֥י הַמֶּֽלֶךְ׃
И король назначил для них ежедневную порцию короля'пищу и вино, которое он пил, и чтобы они питались три года; чтобы в конце они могли предстать перед царем.
Tosefta Shekalim (Lieberman)
A Levite may only enter the court for service if he has studied for five years, for it is said: "This applies to the Levites: from the age of twenty-five" etc. And further the [Scripture] says: ”From the age of thirty”. If it is said: “From the age of twenty-five” why is it said: ״From thirty years”? If it is said: "From the age of thirty" then why is it said: "From the age of twenty-five"? That means that he studied all the time between the age of twenty-five and thirty, from that point in time and onwards he was allowed to work From here it was said: Whoever does not show success in his instruction within five years, R. Jose says three years, because it is said: "To educate you for three years.
II Chronicles
And he exiled the survivors of the sword to Bavel, and they were slaves to him and to his sons until the reign of the kingdom of Paras.