विभाषा धातौ सम्भावनवचनेऽयदि

The affix लिङ् (Benedictive) is optionally used after a verb when it has another verb which expresses 'expectation' in construction with it, but not so when the word यत् is used.
The whole of the last sutra qualifies this sutra; the 'expectation' indicated here being of the kind mentioned in the last sutra and governed by the conditions laid down in that aphorism. The word by which an 'expectation' is expressed such as सम्भावय अपि, or अपिनाम, is called सम्भावन-वचन. This sutra enjoins an option where by the last aphorism, there would have been necessarily the Potential Tense. Thus सम्भावयामि भुञ्जीत or भोक्ष्यते भवान् 'I expect you will eat'; अवकल्पयामि भुञ्जीत or भोक्ष्यते भवान् 'I hope you will eat'; श्रद्दधे भुञ्जीत or भोक्ष्यते भवान् 'I believe you will eat'. But no option is allowed, and the Potential must necessarily be used, when the word यत् is employed. As सम्भावयामि यद् भुञ्जीत भवान् 'I expect you will eat'.

The sutra may also be rendered thus. "The Potential is not necessarily employed where there is in connection with it a verb in the sense of 'to hold as possible', but not when यद् is employed."