Yōga Sūtra 2.23

स्वस्वामिशक्त्योः स्वरूपोपलब्धिहेतुः संयोगः।

svasvāmiśaktyōḥ svarūpōpalabdhihētuḥ saṁyōgaḥ।

[स्व स्वामि शक्त्योः स्वरूपः उपलब्धिः हेतुः संयोगः।
sva = = one's own; svāmi = master's; śaktyōḥ = of two powers; svarūpaḥ = the essence; upalabdhiḥ = obtaining such benefit; hētuḥ = is the caused of; saṁyōgaḥ = the integration;]

The understanding of the essence of one's own self, and that of the master, and the understanding of both their powers, is obtained by Samyōga, i.e. in-unison.

Difference between 'sva', the self, and Svāmi, the master, is to be observed.