BG Chap 11 - Arjuna's desire to see the universal form
Seeing that the source of all the avatāras including Mahā-Viṣṇu was standing in front of him, Arjuna said that his bewilderment was now gone by the Lord’s mercy, which was shown by the description of the vibhūtis. These vibhūtis are very confidential, not understood by anyone except the Lord, whose two eyes are long and reddish at the tips, like lotus petals, and their beauty is intensified by His intense love for His devotees.
Kṛṣṇa had said many times about how the creation and dissolution of all beings arises thru Him. For e.g. ahaṁ kṛtsnasya jagataḥ prabhavaḥ pralayas tathā: ‘I am the creation and destruction of the whole universe’ (BG 7.6). Although He is the creator of everything, Kṛṣṇa does not undergo any change, and remains aloof and unaffected: māyā tatam idaṁ sarvam: ‘I pervade the whole universe; all beings are in Me, but I am not in them’. (BG 9.4). Arjuna accepting whatever Kṛṣṇa had said as true wanted to see the plenary form of Kṛṣṇa that supports the whole universe. He wanted to see that form expressing Kṛṣṇa’s power as the controller of all. Arjuna naturally relishes the sweet form of Kṛṣṇa but now that the Lord desired to assume a sharp taste, Arjuna manifested a desire to experience His majesty and power.
Since the Lord is the Supreme Personality of Godhead, He is present within Arjuna himself; therefore He knows the desire of Arjuna, and He can understand that Arjuna has no special desire to see Him in His universal form, for Arjuna is completely satisfied to see Him in His personal form of Kṛṣṇa. But the Lord can understand also that Arjuna wants to see the universal form to convince others. Arjuna did not have any personal desire for confirmation. Kṛṣṇa also understands that Arjuna wants to see the universal form to set a criterion, for in the future there would be so many imposters who would pose themselves as incarnations of God.