Yōga Sūtra 2.20 and 21
द्रष्टा दृशिमात्रः शुद्धोऽपि प्रत्ययानुपश्यः।
The observer, (the Ishwara), is simply observing, and is pure. Even then, the one who sees later, (the being) undergoes the mental modifications.
तदर्थ एव दृश्यस्यात्मा।
Therefore only, the atman, i.e. Ishwara, is understood to be the observer (, and not the Jeeva).
Note:
The following Rig vedic hymn throws light on this important secret topic, always mentioned cryptically in Vedic literature.
द्वा सुपर्णा सयुजा सखाया समानं वृक्षं परि षस्वजाते। तयोरन्यः पिप्पलं स्वाद्वत्त्यनश्नन्नन्यो अभि चाकशीति॥ -Rig 1.164.20
Two birds associated together, and mutual friends, take refuge in the same tree; one of them eats the sweet fig; the other abstaining from food, merely looks on.
The bird that observes and abstains from food is the lord, the ātman, within the body. The one that gets affected and eats the sweet fig is the being. Both are present within the body.
The following verse from Sankhya Karika becomes relevant here:
रङ्गस्य दर्शयित्वा निवर्तते नर्तकी यथा नृत्यात्। पुरुषस्य तथात्मानं प्रकाश्य विनिवर्तते प्रकृतिः॥ -Sankhya Karika 59
The dancer exhibiting herself returns from the stage after the performance. Similarly, the prakruthi returns after illuminating the ātman (the God) to the purusha (the being).
Observe again similar terminology used here, 'ātman' for the God, and 'purusha' for the being.
