see something with your own eyes idiom
（尤指不是亲眼所见就不会相信）亲眼所见
to see something yourself, especially when it is something that you would not believe to exist or be true if you did not see it
They took all the money and left. I saw it with my own eyes. 我亲眼看见他们把所有的钱拿走后就离开了。
You saw with your own eyes how much he's changed. 你亲眼看到他的变化有多大的。