Bhishma said People do consider a regular fast for a month or a half month as a penance. The truth, however, is that one who mortifies his own body is not to be considered, either as an ascetic or as one conversant with duty.
भीष्म उवाच मासार्धमासोपवासाद् यत् तपो मन्यते जनः। आत्मतन्त्रोपघाती यो न तपस्वी न धर्मवित्॥