There is a Mantra in the Vedas, O son of Kunti, that sanctions it, I describe to you only those practices which are sanctioned by the authority of the Vedas.
इति चाप्यत्र कौन्तेय मन्त्रो वेदेषु पठ्यते। वेदप्रमाणविहितं धर्मं च प्रब्रवीमि ते॥