Verse 31

असत्यमेवासत्यं हि सत्यं सत्यं सदेव हि ।सत्यासत्यमसद्विद्धि तदर्थं किं नु मुह्यसि

In plain words

The unreal is indeed just unreal; the real is real -- it is being itself. Know the real-and-unreal to be non-being: why then are you deluded over it?