None other than Guru Arjan - Partakh Har proclaims that - "Gur Nanak, Nanak Har Soye (Sri Guru Granth Sahib, 864)" (Nanak is My Guru and Nanak is the Lord ALmighty Himself)

Also Listen to the whole kirtan - "Gur Meri Puja, Gur Gobind."

Click to Watch