Brahma-rākṣasas are brāhmaṇas who have not performed their scriptural atonements, who have accepted in charity that which should not be accepted in charity, who have performed sacrifices that are not meant to be performed and other sins and hence have become rākṣasas. When they spot offenses in the performance of the sacrifice, they enter the sacrifice and destroy it. The second half of this verse explains what can happen.