Srimad Bhagavatam Canto 10, Chapter 50, Text 19

SB 10.50.19

sri-bhagavan uvaca
na vai sura vikatthante
 darsayanty eva paurusam
na grhnimo vaco rajann
 aturasya mumursatah
 
Translation: 
 
The Supreme Lord said: Real heroes do not simply boast but rather show their prowess in action. We cannot take seriously the words of one who is full of anxiety and who wants to die.
Srimad Bhagavatam Canto 10, Chapter 50, Text 18
Srimad Bhagavatam Canto 10, Chapter 50, Text 20