On his blog, Matt Schmucker gave his three favorite quotes from John MacArthur at Together For The Gospel
"1. "Soft preaching makes for hard people."
2. "Preachers are the only ones in the world who can take no credit for everything we do (except the mistakes)."
3. "It's not about how cool you are, but how clear you are."
If I remember correctly, MacArthur also pointed out that "Hard preaching makes for soft hearts/people."