Daniel 1:8-20 NKJV
But Daniel purposed in his heart that he would not defile himself with the portion of the king’s delicacies, nor with the wine which he drank; therefore he requested of the chief of the eunuchs that he might not defile himself. Now God had brought Daniel into the favor and goodwill of the chief of the eunuchs. And the chief of the eunuchs said to Daniel, “I fear my lord the king, who has appointed your food and drink. For why should he see your faces looking worse than the young men who are your age? Then you would endanger my head before the king.”
So Daniel said to the steward whom the chief of the eunuchs had set over Daniel, Hananiah, Mishael, and Azariah, “Please test your servants for ten days, and let them give us vegetables to eat and water to drink. Then let our appearance be examined before you, and the appearance of the young men who eat the portion of the king’s delicacies; and as you see fit, so deal with your servants.” So he consented with them in this matter, and tested them ten days.
And at the end of ten days their features appeared better and fatter in flesh than all the young men who ate the portion of the king’s delicacies. Thus the steward took away their portion of delicacies and the wine that they were to drink, and gave them vegetables.
As for these four young men, God gave them knowledge and skill in all literature and wisdom; and Daniel had understanding in all visions and dreams.
Now at the end of the days, when the king had said that they should be brought in, the chief of the eunuchs brought them in before Nebuchadnezzar. Then the king interviewed them, and among them all none was found like Daniel, Hananiah, Mishael, and Azariah; therefore they served before the king. And in all matters of wisdom and understanding about which the king examined them, he found them ten times better than all the magicians and astrologers who were in all his realm.
NKJV: New King James Version