Bg 11.6

paśyādityān vasūn rudrān
aśvinau marutas tathā
bahūny adṛṣṭa-pūrvāṇi
paśyāścaryāṇi bhārata
Synonyms: 
paśya — see; ādityān — the twelve sons of Aditi; vasūn — the eight Vasus; rudrān — the eleven forms of Rudra; aśvinau — the two Aśvinīs; marutaḥ — the forty-nine Maruts (demigods of the wind); tathā — also; bahūni — many; adṛṣṭa — that you have not seen; pūrvāṇi — before; paśya — see; āścaryāṇi — all the wonders; bhārata — O best of the Bhāratas.
Translation: 
O best of the Bhāratas, see here the different manifestations of Ādityas, Vasus, Rudras, Aśvinī-kumāras and all the other demigods. Behold the many wonderful things which no one has ever seen or heard of before.
Purport: 

Even though Arjuna was a personal friend of Kṛṣṇa and the most advanced of learned men, it was still not possible for him to know everything about Kṛṣṇa. Here it is stated that humans have neither heard nor known of all these forms and manifestations. Now Kṛṣṇa reveals these wonderful forms.