When all the demigods requested Indra to kill Vṛtrāsura, he refused because Vṛtrāsura was a brāhmaṇa. The demigods, however, encouraged Indra not to fear killing him because Indra was protected by the Nārāyaṇa-kavaca, or the Supreme Personality of Godhead Himself, Lord Nārāyaṇa. Even by a glimpse of the chanting of Nārāyaṇa’s name, one becomes free from all the sinful reactions of killing a woman, a cow or a brāhmaṇa. The demigods advised Indra to perform an aśvamedha sacrifice, by which Nārāyaṇa would be pleased, for the performer of such a sacrifice is not implicated in sinful reactions even if he kills the entire universe.