Yoga Sūtra Chapter Three verse 4

trayam-ekatra saṃyamaḥ ||4||

The three in the same place is complete restraint.

traya - the threeekatra - in the same placesaṃyama - complete restraint

Commentaries and Reflections

T Krishnamacharya:

The evolution of Samādhi is Sthūla Savitarkā to Sthūla Nirvitarkā.
This is Viniyoga Krama, then Sūkṣma Savicārā to Sūkṣma Nirvicārā.
Commentary to Yoga Sūtra Chapter Three verse 4
Cross referencing to Yoga Sūtra Chapter One verse 42-44.