वासव: Vasava (Indra), राक्षसीम् pertaining to rakshasa, तनुम् body, आस्थाय assuming, पर्वणि on the concluding day of the fornight (fullnew moon), तं यज्ञं यजमानस्य while the sacrificer was performing sacrifice, तस्य Sagara's, यज्ञीयाश्वम् horse relating to sacrifice, अपाहरत् had stolen.

On the concluding day of the fortnight (full moon day) while the sacrifice was being performed, Vasava (Indra) assuming the form of rakshasa, had stolen away Sagara's sacrificial horse.