Ramayana
स त्वं पुरुषशार्दूल मार्गस्व विषयं स्वकम् । दुष्कृतं यत्र पश्येथास्तत्र यत्नं समाचर ॥ 7-74-32 ॥
Therefore you, O tiger among men, search through your own realm; and wherever you should perceive an evil deed, there apply your effort.
english translation