All enlightened ones right from Sage Yajnavalkya and down like Mahavira, Gautama Buddha even Jesus Christ and Prophet Mohammed had seen Brahman after reaching state of enlightenment.
Brahman can be seen only after reaching state of enlightenment, never before. Brahman is beyond reach of religious practitioners, who believed more in Ishvara concept of God than Brahman. Brahman is the underlying absolute reality of cosmic life, the sap of every living form.
Other than above enlightened souls even Adi Shankaracharya, Chaitanya Mahaprabhu and also Eknath, Dnyaneshwar Tukaram Namdev and in recent times Sri Ramakrishna Paramhansa and Maharshi Ramana had seen Brahman in all its glory.
To see Brahman one has to indulge in spirituality as detailed in Bhagavad Gita. One single scripture Bhagavad Gita suffices in present times to reach state of enlightenment.
The enormity of Brahman cannot be conceptualized even by enlightened souls but the essence of cosmic life why Brahman exists, and how Brahman explodes itself with a big bang to form present cosmos, everything becomes crystal clear.
Furthermore it is an absolute fact of spiritual life that God Brahman can never be seen, it can only be realized.