SB 6.11.13

sa taṁ nṛpendrāhava-kāmyayā ripuṁ
 vajrāyudhaṁ bhrātṛ-haṇaṁ vilokya
smaraṁś ca tat-karma nṛ-śaṁsam aṁhaḥ
 śokena mohena hasañ jagāda
Word for word: 
saḥ — he (Vṛtrāsura); tam — him (the King of heaven, Indra); nṛpa-indra — O King Parīkṣit; āhava-kāmyayā — with a desire to fight; ripum — his enemy; vajra-āyudham — whose weapon was the thunderbolt (made from the bones of Dadhīci); bhrātṛ-haṇam — who was the killer of his brother; vilokya — seeing; smaran — remembering; ca — and; tat-karma — his activities; nṛ-śaṁsam — cruel; aṁhaḥ — a great sin; śokena — with lamentation; mohena — by bewilderment; hasan — laughing; jagāda — said.
Translation: 
O King, when the great hero Vṛtrāsura saw Indra, his enemy, the killer of his brother, standing before him with a thunderbolt in his hand, desiring to fight, Vṛtrāsura remembered how Indra had cruelly killed his brother. Thinking of Indra’s sinful activities, he became mad with lamentation and forgetfulness. Laughing sarcastically, he spoke as follows.