At the time of his starting, he had been earnestly ordered by king Yudhishthira the just not to kill those Kshatriyas whose kinsmen had been killed before on the field of Kurukshetra.
स हि वीरः प्रयास्यन् वै धर्मराजेन वारितः। हतबान्धवा न ते पार्थ हन्तव्याः पार्थिवा इति॥