SB 10.89.51

dvāreṇa cakrānupathena tat tamaḥ
 paraṁ paraṁ jyotir ananta-pāram
samaśnuvānaṁ prasamīkṣya phālgunaḥ
 pratāḍitākṣo pidadhe ’kṣiṇī ubhe
Word for word: 
dvāreṇa — by the path; cakra — the Sudarśana disc; anupathena — following; tat — that; tamaḥ — darkness; param — beyond; param — transcendental; jyotiḥ — light; ananta — unlimited; pāram — whose expanse; samaśnuvānam — all-pervasive; prasamīkṣya — beholding; phālgunaḥ — Arjuna; pratāḍita — pained; akṣaḥ — whose eyes; apidadhe — he closed; akṣiṇī — his eyes; ubhe — both.
Translation: 
Following the Sudarśana disc, the chariot went beyond the darkness and reached the endless spiritual light of the all pervasive brahmajyoti. As Arjuna beheld this glaring effulgence, his eyes hurt, and so he shut them.
Purport: 

After breaking through each of the eight concentric shells of the universe, the Sudarśana disc led Lord Kṛṣṇa’s chariot into the limitless, self-effulgent atmosphere of the spiritual sky. This journey by Lord Kṛṣṇa and Arjuna to Vaikuṇṭha is also narrated in Śrī Hari-vaṁśa, where the Lord is quoted as telling His companion:

brahma-tejo-mayaṁ divyaṁ
 mahat yad dṛṣṭavān asi
ahaṁ sa bharata-śreṣṭha
 mat-tejas tat sanātanam

“The divine expanse of Brahman effulgence you have seen is none other than Myself, O best of the Bhāratas. It is My own eternal effulgence.”

prakṛtiḥ sā mama parā
 vyaktāvyaktā sanātanī
tāṁ praviśya bhavantīha
 muktā yoga-vid-uttamāḥ

“It comprises My eternal, spiritual energy, both manifest and unmanifest. The foremost yoga experts of this world enter within it and become liberated.”

sā sāṅkhyānāṁ gatiḥ pārtha
 yogināṁ ca tapasvinām
tat paraṁ paramaṁ brahma
 sarvaṁ vibhajate jagat
mamaiva tad ghanaṁ tejo
 jñātum arhasi bhārata

“It is the supreme goal of the followers of Sāṅkhya, O Pārtha, as well as that of the yogīs and ascetics. It is the Supreme Absolute Truth, manifesting the varieties of the entire created cosmos. You should understand this brahma-jyoti, O Bhārata, to be My concentrated personal effulgence.”