not take your eyes off somebody/something
not take (one's) eyes off (someone or something)
1. Literally, to look at someone or something continually and at length, especially in a transfixed or captivated manner. The juxtaposition of colors in that painting is so strange that you can't take your eyes off it. I couldn't take my eyes off the car accident. Even though it was horrific, it was almost spellbinding to look at.
2. To keep someone or something under continuous surveillance. The IRS won't be taking their eyes off you now that they know you've tried to avoid taxes in the past. I can't take my eyes off my son for a second or he'll wander off and get into trouble.