can you name some texts that expound this in the classical period?
Rig Veda,  Upanishad
Yoga
The first use of the root of the word "yoga" is in hymn 5.81.1 of the Rig Veda, a dedication to the rising Sun-god in the morning (Savitri), where it has been interpreted as "yoke" or "yogically control".

The earliest evidence of Yogis and Yoga tradition is found in the Keśin hymn 10.136 of the Rigveda, states Karel Werner.
who is believed to be the originator of yoga Ancient India traditionally, what is the primary aim of this exercise? The ultimate goal of Yoga is "Moksha" (liberation), although the exact form this takes depends on the philosophical or theological system with which it is conjugated.
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Yoga [SEP] Textual references
The first use of the root of the word "yoga" is in hymn 5.81.1 of the Rig Veda, a dedication to the rising Sun-god in the morning (Savitri), where it has been interpreted as "yoke" or "yogically control". The earliest evidence of Yogis and Yoga tradition is found in the Keśin hymn 10.136 of the Rigveda, states Karel Werner. The Rigveda, however, does not describe yoga, and there is little evidence as to what the practices were. Early references to practices that later became part of yoga, are made in Brihadaranyaka Upanishad, the earliest Hindu Upanishad. For example, the practice of pranayama (consciously regulating breath) is mentioned in hymn 1.5.23 of Brihadaranyaka Upanishad (c.