Where does the Buddha say 'you will be punished by your anger'?
The fakebuddhaquotes web site attributes it as follows:

Going back to 1993, we hit pay dirt! In To Love Is to Know Me: The Bhagavad Gita for Daily Living (Volume 3), author Eknath Easwaran says the following:

Even more intriguing to me is the karma of our health. Again, let me illustrate one or two kinds of connection. For one, the Buddha says that we are not punished for our anger, we are punished by our anger. In other words, anger is its own karma.

Note the absence of quotation marks. Eknath is not quoting the Buddha, but paraphrasing his teachings on anger and karma.