the apple of somebody's eye

the apple of (one's) eye

A cherished or favored person. This phrase is thought to be Biblical in origin. My nephew is just the apple of my eye. He has five kids, but his only daughter is clearly the apple of his eye.
See also: apple, eye, of

the ˌapple of somebody’s ˈeye

a person, usually a child, who somebody loves very much; a favourite child: The second child, John, was the apple of his mother’s eye.In the past, the pupil (= the small round black area at the centre of the eye) was called the ‘apple’ of the eye, the part that had to be protected most carefully.
See also: apple, eye, of