भूते च

And (where there is a reason for affixing लिङ् (Benedictive) , the affix ऌङ् (Conditional Future) is to be used, when the non-completion of the action is to be understood) if the sense is that of past time.
The whole of the last aphorism is understood in this. The last sutra enjoined लृङ् in the Future tense; this sutra ordains it in the Past, the Conditional tense having both these significations. The reasons for affixing लिङ् are given in sutras 3.3.152 and those that follow it. In sutra 3.3.141 and those that follow, as far as 3.3.152, optional rules for the employment of the Conditional tense will be given. Thus:- दृष्टो मया भवत्पुत्रोऽन्नार्थी चङ्क्रम्यमाणः अपरश्च द्विजो ब्राह्मणार्थी, यदि स तेन दृष्टोऽभविष्यत्, तदाऽभोक्ष्यत, न तु भुक्तवान्, अन्येन पथा स गतः । 'I saw your son, wandering about in search of food, I saw also a twice-born in search of a Brahmana(whom he would feast); if he (your son) had been seen by him (the twice-born), then he would have been fed; but as a matter of fact, he has not been fed, he went by a different road'.

The conditional sentence यदि स तेन दृष्टोऽभविष्यत् तदाऽभोक्ष्यत is employed under circumstances set out above. It refers to a past time, there is the relation of cause and effect existing, one being in search of food, and another in search of a guest to feed; and the action is not completed; both taking different roads, did not come across each other.