Thirukkural 638

அறிகொன்று அறியான் எனினும் உறுதி உழையிருந்தான் கூறல் கடன்.

Arikkondu arivaan eninum uruti Uzhai irundhaan kuraral kadan.

Even if the one of steadfast labor does not know what it is right to say, it remains his duty to speak—for constancy itself is his knowledge.