sādhyāvinābhāvitā hetulakṣaṇam, taccāvinābhāvitvaṃ sādhyāsiddhau na siddhamityasiddho hetuḥ, ubhayasiddhināntarīyakatvād avinābhāvitvasya /
inseparability from the sādhya is the definition of hetu, and this inseparability cannot be established when the sādhya is not established; thus the hetu is unestablished, because inseparability necessarily depends on the establishment of both.