स्वरूपबोधेन ईक्षते पश्यति सर्वमिति साक्षी ।'साक्षाद्द्रष्टरि संज्ञायाम्' इति पाणिनिवचनादिनिप्रत्ययः ।क्षेत्रं शरीरं जानातीति क्षेत्रज्ञः; 'आतोऽनुपसर्गे कः' इति कप्रत्ययः ।'क्षेत्रज्ञं चापि मां विद्धि' इति भगवद्वचनात् ।'क्षेत्राख्यानि शरीराणि तेषां चैव यथासुखम् ।तानि वेत्ति स योगात्मा ततः क्षेत्रज्ञ उच्यते' इति ब्रह्मपुराणे ।स एव न क्षरतीति अक्षरः परमात्मा ।अश्नोतेर्वा सरप्रत्ययान्तस्य रूपमक्षर इति ।एवकारात् क्षेत्रज्ञाक्षरयोरभेदः परमार्थतः, 'तत्त्वमसि' इति श्रुतेः ।चकाराद्व्यावहारिको भेदश्च, प्रसिद्धेरप्रमाणत्वात् ॥योगो योगविदां नेता प्रधानपुरुषेश्वरः ।नारसिंहवपुः श्रीमान् केशवः पुरुषोत्तमः ॥ १६ ॥'ज्ञानेन्द्रियाणि सर्वाणि निगृह्य मनसा सह ।एकत्वभावना योगः क्षेत्रज्ञपरमात्मनोः' तदवाप्ततया योगः इति योगविदो विदुः ।योगं विदन्ति विचारयन्ति, जानन्ति, लभन्ते इति वा योगविदः ।तेषां नेता ज्ञानिनां योगक्षेमवहनादि
In plain words
Sākṣin is the witness who beholds everything through the direct awakening of his own nature. Kṣetrajña is the knower of the field, the physical body, as Krishna declares in the Gītā: 'Know me also to be the knower of the field in all fields.' Akṣara is the indestructible Supreme Self who never perishes. Because of the word eva in scripture, absolute non-difference between the individual soul and the supreme is established by the great utterance 'Tat tvam asi', while the word ca acknowledges a relative, practical distinction that lacks ultimate reality. Yoga is the meditative realization of the oneness of the individual soul and the Supreme Self, attained by restraining the senses and mind. Netā is the guide of those who know yoga, carrying out their spiritual acquisition and preservation as promised by the Lord.
Close to the Sanskrit
Sākṣī: seeing everything by the awakening of true nature; the suffix 'ini' is added in the sense of a direct seer by Panini's rule. Kṣetrajñaḥ: one who knows the field, the body; the suffix 'ka' by 'āto'nupasarge'; from the Bhagavad Gītā 'And know me also as the knower of the field'; and from the Brahma Purāṇa 'Bodies are called fields, he knows them as he pleases, that yogātmā, hence he is called kṣetrajña'. Akṣaraḥ: the Supreme Self who does not perish; or the form of akṣara ending in the suffix 'sara' from the root aś. Due to the particle 'eva', non-difference between kṣetrajña and akṣara is absolute, by the śruti 'Tat tvam asi'; and due to 'ca', empirical difference exists, though conventional and without ultimate proof. Yoga, Yogavidām Netā, Pradhānapuruṣeśvaraḥ, Nārasiṃhavapuḥ, Śrīmān, Keśavaḥ, Puruṣottamaḥ. Yoga: having restrained all sensory organs along with the mind, the contemplation of oneness of the kṣetrajña and Paramātmā is yoga; yoga is so called by attaining that, as knowers of yoga know. Yogavidaḥ: those who know, investigate, know, or attain yoga. Their leader: carrying the acquisition and preservation for the wise.