Daniel 1:14-18

So he listened to them in this matter, and put them to the test for ten days.

And at the end of ten days their appearance seemed better, and they were fatter than all the youths who had been eating the king’s choice food.

So the overseer continued to withhold their choice food and the wine they were to drink, and kept giving them vegetables.

And as for these four youths, God gave them knowledge and intelligence in every kind of literature and expertise; Daniel even understood all kinds of visions and dreams.

Then at the end of the days which the king had specified for presenting them, the commander of the officials presented them before Nebuchadnezzar.