sarva-bhūteṣu yenaikaḿ
bhāvam avyayam īkṣate
avibhaktaḿ vibhakteṣu
taj jñānaḿ viddhi sāttvikam

Translation of Bhagavad Gita 18.20

That knowledge by which one undivided spiritual nature is seen in all living entities, though they are divided into innumerable forms, you should understand to be in the mode of goodness.

Commentary by Sri A.C. Bhaktivedanta Swami Prabhupada of Gaudiya Sampradaya:

A person who sees one spirit soul in every living being, whether a demigod, human being, animal, bird, beast, aquatic or plant, possesses knowledge in the mode of goodness. In all living entities, one spirit soul is there, although they have different bodies in terms of their previous work. As described in the Seventh Chapter, the manifestation of the living force in every body is due to the superior nature of the Supreme Lord. Thus to see that one superior nature, that living force, in every body is to see in the mode of goodness. That living energy is imperishable, although the bodies are perishable. Differences are perceived in terms of the body; because there are many forms of material existence in conditional life, the living force appears to be divided. Such impersonal knowledge is an aspect of self-realization.

Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

This verse speaks of sattvika process of knowing. Seeing one soul (ekam bhavam), with one form (avibhaktam) which is indestructible (avyayam) residing one by one in different forms (vibhaktesu) such as human, devata, or animal for the purpose of enjoying various fruits, which are temporary, through knowledge related to action (verse 18), is known as sattvika knowledge.

Commentary by Sri Ramanuja of Sri Sampradaya:

18.20 The self (Atman), which is of the form of knowledge, is alike and uniform, though distinct, in all beings, even though they may externally, and from the point of view of duty, be distinguished as Brahmanas, Ksatriyas, householders, celibates, fair, tall etc. The immutable selves in all these perishing forms or bodies are unaffected by the fruits of actions. Such knowledge of the immutability of the self in all changing beings, is Sattvika.

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

Lord Krishna explains the threefold nature of knowledge commencing with sattva guna or mode of goodness. The knowledge by which one perceives in all jivas or embodied beings, the one immutable, undivided, imperishable and eternal atma or immortal soul existing within all from the highest demigod Brahma the secondary creator down to immovable entities which are distinguishable from each other is situated in sattva guna.

Commentary by Sri Madhvacharya of Brahma Sampradaya:

The single reality pervading all existence is the Supreme Lord Krishna the creator, maintainer and energiser of all existence. All creation is situated within Him and He is also within every atom of creation. Living entities in the state of bondage or liberation, they are all under His jurisdiction but those who have achieved moksa or liberation from material existence are promoted to the eternal spiritual worlds. The Supreme Lord although manifesting and residing within unlimited variegated forms simultaneously in an all pervading way; yet He distinctly separate from every jiva or embodied being of all gradations. Those jivas whose gradation is material such as trees are distinct unique amongst themselves such as Palm trees, mango trees, apple trees, etc. which although manifesting from the Supreme Lord’s potencies are all distinctly different from the Supreme Lord. This is the knowledge of distinctive characteristics and when developed into wisdom is situated in sattva guna the mode of goodness from whence arises moksa.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

Lord Krishna speaks of three types of knowledge determined by the three gunas or modes of material nature beginning with sattva guna or mode of goodness. One who while performing activities perceives the one undivided, immutable and imperishable nature in the form of the atma or immortal soul residing within all jivas or embodied beings simultaneously such as demigods, humans, animals, spirits, etc. which are merely exhibiting unlimited varieagated forms according to species and genre is one who is firmly situated in sattva guna.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

18.20 Viddhi, know; tat, that; jnanam, knowledge, realization of the Self as non-dual, complete realization; to be sattvikam, originating from sattva; yena, through which knowledge; iksate, one sees; ekam, a single; avyayam, undecaying-that which does not undergo mutation either in itself or by the mutation of its qualities-‘ i.e. eternal and immutable; bhavam, Entity-the word bhava is used to imply an entity-, i.e. the single Reality which is the Self; sarvabhutesu, in all things, in all things begining from the Unmanifest to the unmoving things; and through which knowledge one sees that Entity to be avibhaktam, undivided; in every body, vibhaktesu, in all the deversified things, in the different bodies. The idea is: that Reality which is the Self remains, like Space, undivided. Being based on rajas and tamas, those that are the dualistic philosophies are incomplete, and hence are not by themselves adequate for the eradication of worldly existence.

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

18-20-22 Sarvabhutesu etc. upto samudahrtam. In the classified ones : i.e., [classified] as gods, human beings, etc. Considers as [really] different : i.e., with the thought ‘Here on this depends my pleasure; here in that lies my displeasure’. Without reason : To take recourse to wrath, desire etc., slavishly under the influence of one’s own addiction and also without examining the cause, in named as a thing born of the Tamas (Strand).

Sanskrit Shloka Without Transliteration Marks:

sarva-bhutesu yenaikam
bhavam avyayam iksate
avibhaktam vibhaktesu
taj jñanam viddhi sattvikam

Sanskrit to English Word for Word Meanings:

sarva-bhūteṣu — in all living entities; yena — by which; ekam — one; bhāvam — situation; avyayam — imperishable; īkṣate — one sees; avibhaktam — undivided; vibhakteṣu — in the numberless divided; tat — that; jñānam — knowledge; viddhi — know; sāttvikam — in the mode of goodness.