Transliteration
vedāhaṃ samatītāni vartamānāni cārjuna |
bhaviṣyāṇi ca bhūtāni māṃ tu veda na kaścana || 26 ||
Translation
I know all beings, O Arjuna, that have been in the past, those now in the present and those yet to come; but no one knows Me.
Purport
After explaining different kinds of worships offered to different deities and that all deities originated from him and so all worship ultimately reach to him, Bhgvan Shri Krishna now explains the supreme truth.
He is the origin of everything, all beings, and all deities. It is possible for some human or even deity to know some glory of Bhagvan Shri Krishna, but knowing God completely is not possible. What we know about Shri Krishna is a small portion of his glory which he displays to deities and humans by his own will.