 अहंनियममातिष्ठे सिध्यर्थं पुरुषर्षभ।तस्य विघ्नकरौ द्वौ तु राक्षसौ कामरूपिणौ।। 
 O best among men for the successful completion of a sacrifice I took up a selfimposed  religious observance. Two rakshasas, capable of assuming forms at will, are creating impediments to that sacrifice. 