B.G 11.20

dyāvāpṛthivyoridamantaraṁ hi vyāptaṁ tvayaikena diśaśca sarvāḥ. dṛṣṭvā'dbhutaṁ rūpamugraṁ tavedaṁ lokatrayaṁ pravyathitaṁ mahātman ॥20॥

The space between heaven and earth is indeed pervaded by you alone, and all the directions. Having seen your wondrous and terrible form, the three worlds are agitated, O one great-being.

Gīta Tātparya 11.20

The infinite qualities of the lord are repeated several times, to indicate His infinite attribute in terms of space, qualities, and time. It is also meant to reiterate its significance. The wondrous universal form in general is fearsome, but not so for knowers of Brahman.

dyāvāpṛthivyorantaramekenaiva rūpeṇa vyāptam. "nāntaṁ na madhyam" ityuktatvāt punaḥ "anādimadhyāntam" iti guṇānantyāpekṣayā. "tvayā tataṁ viśvamanantarūpa" iti kālāpekṣayā. svayamantaṁ vidyamānamapi na paśyatītyāśaṅkya "tvayā tataṁ viśvamanantam" ityāha. anyat tātparyajñāpanāya abhyāsarūpam.

Since "neither end nor middle" (nāntaṁ na madhyam) is stated and again "beginningless, middle-less, endless" (anādimadhyāntam) is stated. The first instance shows the space between heaven and earth is pervaded by one form alone. The second indicates infinite qualities. "You have pervaded the universe with infinite forms" (tvayā tataṁ viśvamanantarūpa) refers to time-aspect. Though the end exists, it is not seen, thus it is said "You have pervaded the infinite universe." Otherwise, repetition is used to reiterate the intended meaning.

Note: The verb form "ततम्" (spread/pervaded) is perfect participle — indicating a completed yet continuous state. This suggests that the pervasion is not a onetime event, but a timeless reality, already done and always active.

"sarvaṁ samāpnoṣi tato'si sarvaḥ" iti "sarvaṁ khalvidaṁ brahma" ityādiṣu sarvaśabdavyākhyānarūpam॥

“You pervade all, therefore you are all” is an interpretation of 'all' in the phrase “All this indeed is Brahman” ( sarvaṁ khalvidaṁ brahma).

"trilokeṣu sthitaiḥ bhaktairarjunāya pradarśitam. dṛṣṭaṁ viṣṇorviśvarūpaṁ svayogyatvānurūpataḥ॥"

"The universal form of Viṣṇu was shown to Arjuna by devotees situated in the three worlds, and seen according to one’s eligibility."

prāyaḥ sahaiva pārthena prāyo bhītāśca te'khilāḥ. darśanābhyāsato dṛṣṭirānandodrekatā bhavet॥

Generally, all those who saw it with Pārtha were frightened. But through practice of vision, blissful sight may arise.

tasmin kāle tu bhūmeśca bhārahārārthamudyamāt. ugratvamiva sarvatra na bhītiḥ brahmadarśinām॥

At that time, due to the earth’s effort to relieve her burden, there appeared fierceness everywhere, yet there was no fear for the knowers of Brahman.

arjunādadhikā ye tu teṣāṁ bhītirna cābhavat. śrībrahmarudrapūrvāṇāṁ kṛṣṇāyā bhīmarāmayoḥ॥

Those greater than Arjuna had no fear — such as Śrī, Brahmā, Rudra, Kṛṣṇā, Bhīma, and Rāma."

ityāgneyavacanāt.

- stated thus in the statememnt of Āgneya Purāna.

"dṛṣṭvādbhutaṁ rūpam" ityādi yujyate ॥20॥

“Having seen the wondrous form” - such phrases are appropriate for the context.