Yoga Sūtra Chapter Three verse 4
त्रयमेकत्र संयमः ॥४॥
trayam-ekatra saṃyamaḥ ||4||
The three in the same place is complete restraint.
traya - the three, triple, threefold, consisting of 3, of 3 kindsekatra - jn one, in one and the same; in the same place, in a single spot; all togethersaṃyama - complete restraintCommentaries and Reflections
Commentary by 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.
Commentary by TKV Desikachar:
“Ekatra refers to the choice
of one thing and going into
that over a period of time.
So, only one direction
regularly in the practice of
Dhāraṇā, Dhyānā and Samādhi.”
Commentary by S Ramaswami:
“The object has completely come under the control of the mind.
When the three are one object that is called Saṃyama.
One starts with Dhāraṇā which leads to Dhyāna and to Samādhi.
This is with respect to the same time and object.”