SB 6.13.7

hayamedhena puruṣaṁ
 paramātmānam īśvaram
iṣṭvā nārāyaṇaṁ devaṁ
 mokṣyase ’pi jagad-vadhāt
Word for word: 
hayamedhena — by the sacrifice known as aśvamedha; puruṣam — the Supreme Person; paramātmānam — the Supersoul; īśvaram — the supreme controller; iṣṭvā — worshiping; nārāyaṇam — Lord Nārāyaṇa; devam — the Supreme Lord; mokṣyase — you will be liberated; api — even; jagat-vadhāt — from the sin for killing the whole world.
The ṛṣis continued: O King Indra, by performing an aśvamedha sacrifice and thereby pleasing the Supreme Personality of Godhead, who is the Supersoul, Lord Nārāyaṇa, the supreme controller, one can be relieved even of the sinful reactions for killing the entire world, not to speak of killing a demon like Vṛtrāsura.