Daniel 1:5

And the king appointed them a daily provision of the king's
meat
Every day a portion was ordered them, from the king's table, of the richest dainties he himself ate of; which was done not only as an act of royal munificence and generosity, and in respect of their birth and breeding; but also as a bait and snare to allure and entice them, to make them in love with the country and condition in which they were, and to forget their own; as well also in order to preserve their well favoured look and good complexion, and fit them for their study of language and literature; which might be hindered for want of the necessaries of life, or by living on gross and coarse food: and of the wine which he drank;
which, as it was of various sorts, so of the best and most excellent; and which, moderately drank, conduces to the health of the body, and cheerfulness of the mind; and which are both useful to forward learned studies: so nourishing them three years;
this was the time fixed for their acquiring the learning and language of the Chaldeans; during which they were to be provided for from the king's table, and at his expense, as above; which term of time was judged sufficient for their learning everything necessary to qualify them for the king's service; and in which time it might be thought they would forget their own country, customs, religion, and language, and be inured to the place and persons where they were, and be satisfied and easy with their condition and circumstances: that at the end thereof they might stand before the king;
that is, at the end of three years they might be presented to the king for his examination and approbation, and be appointed to what service he should think fit; and particularly that they might be in his court, and minister to him in what post it should be his pleasure to place them. Some in Aben Ezra, and which he himself inclines to, read and interpret it, "that some of them might stand before the king"; such as he should choose out of them, that were most accomplished and most fit for his service; so Jacchiades.