Bhashya
समानमन्यत् ।मातरो जनयित्र्यः अतीताः सुखहेतु-भूताः सामर्थ्यात् ।न हि दुःखहेतुभूतासु ग्रामसूकरादिज-न्मनिमित्तासु मातृषु विशुद्धसत्त्वस्य योगिनः इच्छा तत्सं-बन्धो वा युक्तः ॥
In plain words
The rest of the explanation is identical. By implication, the 'mothers' referred to here are those past maternal figures who brought joy. For it is impossible that a yogi of completely purified mind would ever desire or hold a connection with mothers who brought only pain—such as those responsible for births in the form of village pigs and other low creatures.
Close to the Sanskrit
The rest is the same. The mothers, the past progenitresses, who have become the cause of happiness, [are meant here] by implication. Indeed, the desire or connection of a yogi of purified mind with mothers who have become the cause of pain, who are the causes of births such as village pigs, is not proper.