Guru Nanak incarnation of the primordial guru or master who taught morality and balance in preparation for spiritual ascent. He sought neither to unite religions nor to create a new one, but taught that spiritual liberation can be achieved through inward meditation.
See also: Ten Primordial Masters
Like we had a doctor who came all the way from Iran and that day I was very tired, very tired and I told him that, “You have to become a Sikh gentleman if you want to become all right. And I cannot help you much because you do not believe that there is anybody else but Mohammed Sahib.” Then he got very angry and I said, “I am really very tired and in one sentence I want to finish it because I am really very tired.” So he went away and he came back next day and started arguing with Me. He said, “What do You mean by this?” I said, “I mean that Mohammed Sahib and Guru Nanak are the same personalities.” He said, “How do You say that?” I said, “It is said that once Guru Nanaka was lying down and people said that, ‘Sir, your feet are towards Mecca.’ So He said, ‘All right I’ll turn this side.’ He turned on the other side and Mecca was on the other side. What does that mean? That means that Mecca is at the feet of Mohammed Sahib, also at the feet of Shri Guru Nanaka. That means both of them are the same personalities and if you want to argue with Me, I cannot tell you how, but I will tell you one thing, that if you want to get cured of your cancer of your stomach, then you have to believe in Guru Nanak.” He said, “I can’t believe in Guru Nanak”. I said, “I cannot cure you, I am sorry, I just can’t help you.” He went home, his wife was a wiser woman, she said, “My husband is going to die now.” He said, “All right, why not believe in Guru Nanak? Let’s see what happens.” So he came down after three, four days when he had very bad time and he said, “Mother all right, now we like to know about Guru Nanak.” So I told him about the greatness of Guru Nanak. Why He came on this earth. Because He found that what Mohammed Sahib had done is undone by Muslims. So He came down to tell the Indians about Mohammed Sahib and about other gurus and to bring a unity of Hindu and Muslims. But you can see now what’s happening to that also.
Guru Nanaka always talked of Sahaja Yoga. Everything else, he said, is just showing off. About religion he said that observing fasts, going on pilgrimage, etc., are just meant to show off. Now you have to discover the power that is within you and establish it. Guru Nanaka kept on repeating the same thing again and again. He never talked of rituals: But when Guru Teg- Bahadur came, war with Mohammadan Rulers was being fought. So he prescribed Kada (iron bangle), sword (kripan) to keep them in the state of preparedness. But Guru Nanaka always talked of the spirit. He explained it very clearly, but no one heeded what he wrote. They will just put a finger on the couplet and read it out. Could we understand him this way? If we go through his writings properly and absorb it, then the whole Shabad-Jalam (confusion), in which most of the people are caught, will come to an end. See the condition of Sikhs ! Without looking within and experiencing the innate energy, how could one follow Sikh religion? Only this is the teaching of Guru Nanaka, this is what is called `Sikh’ (learning). All the saints of that age had the discretion to know who is a saint and who is not. All the Gurus incorporated their poems and experiences in Guru Grantha and that is why Guru Grantha is revered so much. Only the renowned Gurus contributed to it. They were so spiritual that they did churning of all the religious scriptures and put the substance in Guru Grantha.