śakra-hā bhavitā sutaḥ

samvatsaram-for one year; pumsavanam-called pumsavana; vratam-vow; etat-this; aviplutam-without violation; dharayisyasi-you will perform; cet-if; tubhyam-for you; sakra-ha-the killer of Indra; bhavita-will be; sutah-a son.