Srimad Bhagavatam Canto 10, Chapter 68, Text 47

SB 10.68.47

kopas te ’khila-siksartham
 na dvesan na ca matsarat
bibhrato bhagavan sattvam
 sthiti-palana-tatparah
 
Translation: 
 
Your anger is meant for instructing everyone; it is not a manifestation of hatred or envy. O Supreme Lord, You sustain the pure mode of goodness, and You become angry only to maintain and protect this world.
 
Purport: 
 
The Kurus admit that Lord Balarama’s anger was entirely appropriate and in fact was meant for their benefit. As Srila Visvanatha Cakravarti puts it, the Kurus meant to say, “Because You exhibited this anger, we have now become civilized, whereas previously we were wicked and could not see You, blinded as we were by pride.”
Srimad Bhagavatam Canto 10, Chapter 68, Text 46
Srimad Bhagavatam Canto 10, Chapter 68, Text 48