SB 6.12.6
indro na vajram jagrhe vilajjitas
cyutam sva-hastad ari-sannidhau punah
tam aha vrtro hara atta-vajro
jahi sva-satrum na visada-kalah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Having dropped the thunderbolt from his hand in the presence of his enemy, Indra was practically defeated and was very much ashamed. He dared not pick up his weapon again. Vrtrasura, however, encouraged him, saying, “Take up your thunderbolt and kill your enemy. This is not the time to lament your fate.”