Bhagavad-Gita: Chapter 7, Verse 21

Rudra Vaisnava Sampradaya:

Visnuswami

Sridhara Swami's Commentary

Amongst those who worship a particular demigod which represents a potency of Lord Krishna then He as paramatma the Supreme Soul within all sentient beings monitoring every thought and action, makes such devotees faith steady and stable. Of others who worship illusory gods, His external potency known as Maya the deluding illusory energy keeps them steadily following the illusion of their erroneous philosophies and speculative theosophies that have no validity not being verified as bonafide in the Vedic scriptures.

Brahma Vaisnava Sampradaya:

Madhvacarya

Madhvacarya's Commentary

The words yam yam tanum means according to whichever demigod such as Brahma the architect of creation, Indra the celestial chief, or Laxsmi the goddess of wealth. The Narada Purana states: There will be cessation to the votaries of Brahma and others due to their temporary nature; but for the devotees of the Supreme Lord Krishna there is no cessation due to His eternal nature. What is the goal of moksa or liberation from the cycle of birth and death? Where does the atma or soul go after attaining moksa? All these considerations are deliberated upon in the chapters of the Bhagavad- Gita dealing with liberation. Even though the avatars or incarnations of the Supreme Lord are numerous and His expansions are unlimited, moksa is guaranteed and assured to the devotee who devoutly worships any one of them. This has been revealed in the Brahma Vaivartaka Purana.

Sri Vaisnava Sampradaya:

Ramanuja

Ramanuja's Commentary

The demigods such as Indra the celestial chief, Surya the sungod and all others constitute the body of the Supreme Lord as stated in the Taittiriya Upanisad V.I. Although those who worship the demigods are ignorant of this truth as declared in Vedic scriptures. In the Brihad-aranyaka Upanisad V.VII.IX beginning ya aditye tish than yam adityo na veda it states: Who is seated in the sun, but whom the sun knoweth not, whom the sun is comprised of etc. Whomsoever wishes to worship the demigods, the Supreme Lord sanctions that they have unwavering and stable faith in that endeavour because that very faith is given to that which is a part of my universal form and constitutes the Supreme Lord Krishna's body.

Kumara Vaisnava Sampradaya:

Nimbaditya

Kesava Kasmiri's Commentary

If one were to propound that the Supreme Lord is the aggregate of all the demigods and that the demigods are the forms of the Supreme Lord as well. This argument is refuted by Lord Krishna stating yam yam tanum meaning whichever form of demigod or other gods that one craves for some reward seeking to gratify their desires by worshipping or causing others to worship; it is the Supreme Lord only and who keeps the faith of that individual directed towards the very demigod that one contemplates, keeping it firm and steady based upon their latent tendencies from innumerable previous lives. But it should be noted that although Lord Krishna is the Supreme Lord of all, possessing absolute power over everything in existence; He never exerts even the slightest influence over any embodied being to put their faith and devotion in Him.