Imam Ali (AS): The holy Quran is undefeatable
Imam Ali (AS) said: The book of Allah (SWT) which is amongst you is a speaker/communicator whose tongue will never get tired of talking about the truth, and is always expressive. The book of God is clear, articulate and eloquent. It is like a house which its pillars/columns will never collapse, and is the possessor of such greatness and strength that its friends/helpers will never be defeated [1].
[1] Nahjul Balaghah, Sermon 133.
