दाहको नैव दाह्यं स्याद्दाह्यं तद्वन्न दाहकः ।नैवात्मायमनात्मा स्यादनात्मायं न चात्मकः ॥ २१ ॥
In plain words
What burns is never the thing it burns; and the thing that burns is never the fire. In exactly that way: this ātman is never the anātman, and this anātman never has the nature of the ātman.
Close to the Sanskrit
The burner would never be the burnable; likewise the burnable is not the burner. Just so, this Self would never be the non-Self, and this non-Self is not of the nature of the Self.