Listen before you speak

ईक्षणं द्विगुणं प्रोक्ताम्
भाषणस्येति वेधसा ।
अक्षि द्वे मनुष्याणाम्
जिव्हा त्वैकेव निर्मिता ॥

It is said that perceiving (and understanding) is twice as much important as speaking. This is why the creator (or nature) has provided us with two eyes, and just one tongue.

Listen before you speak.