apple of 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.
apple of (one's) eye
One that is treasured: Her grandson is the apple of her eye.
apple of one's eye, the
A cherished person or thing. The term comes from the ancient concept that the eye’s pupil was a solid, apple-shaped body, and, being essential to sight, was precious. It appears in the Bible (Deuteronomy 32:10): “He [the Lord] kept him [Israel] as the apple of his eye.”