Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 19
Sanskrit:
श्रीभगवानुवाचवृथा त्वं कत्थसे मन्द न पश्यस्यन्तिकेऽन्तकम् ।पौरुषं दर्शयन्ति स्म शूरा न बहुभाषिण: ॥ १९ ॥
ITRANS:
śrī-bhagavān uvācavṛthā tvaṁ katthase mandana paśyasy antike ’ntakampaurusaṁ darśayanti smaśūrā na bahu-bhāṣiṇaḥ
Translation:
The Supreme Lord said: O dullard, you boast in vain, since you fail to see death standing near you. Real heroes do not talk much but rather show their prowess in action.