YV 1.2g

He who has foes should in strife offer to Visnu and Varuna a cow [4], to Indra a bull; verily causing his foe to be seized by Varuna, by Visnu, the sacrifice, he drives him away, he appropriates his power by means of that for Indra, he prospers, his foe is defeated. Indra slew Vrtra; him Vrtra slain bound with sixteen coils; from the head of Vrtra came out cows, they were (cows) of Videha; behind them came the bull. It Indra [5] perceived; he reflected, 'He who shall offer him shall be freed from this evil'; he offered to Agni one with a black neck, to Indra a bull. Agni, being approached with his own share, burned into sixteen pieces the coils of Vrtra, and by (the offering) to Indra he bestowed power on himself. He who is seized by evil should offer (a beast) with a black neck to Agni, and a bull to Indra; verily Agni, being approached with his own share [6], burns away his evil, and by (the offering) to Indra he bestows power on himself, he is freed from the evil, he prospers. He who is long in exile should offer a cow to sky and earth; for he is not established in them; verily also he who is long in exile has recourse to sky and earth with their own share; verily they establish them; he is established. It is one which is long in labour, for Iong in labour as it were is the kingdom of him who is long in exile; (verily it serves) for prosperity. To Vayu [7] he should offer a calf; Vayu is their calf; these worlds are barren for him, the people are barren; verily also he who is long in exile has recourse to Vayu with his own share; verily Vayu causes these worlds and the people to give to him; these worlds drop milk for him; the people wait upon him in service. Indra opened the hole of Vrtra; the topmost cattle he grasped by the back and pulled out; a thousand cattle followed it, it became hump backed.