vratam etat suduṣkaram

atha-thereafter; indram-to Indra; aha-spoke; tata-dear one; aham-I; adityanam-to the Adityas; bhaya-avaham-fearful; apatyam-a son; icchanti-desiring; acaram-executed; vratam-vow; etat-this; su-duskaram-very difficult to perform.