The following is found on the single page entitled “Omission” that is just between Parts I and II of Likutei Moharan, the Writings of Rebbe Nachman.
“Echad Haya Avraham”, One Was Abraham, is part of the verse in Ezekiel 33: 24.
And these 3 words have become a Chassidic “mantra” – they are the essence of Judaism.
One was Abraham – that Abraham served Hashem only by that he was one, and thought in his mind that he was the only one in the world, and did not look at all on the people of the world, who turn away from Hashem and obstruct him, and not on his father and the other obstructers, only as if he is the only one in the world, and that is [the explanation of]: One Was Abraham. And such is for all who want to enter into the Service of Hashem, it is impossible to enter except by way of this concept that one should think that there is no one in the world but he singularly alone in the world, and not look at any person who obstructs him, such as his father and mother or his father-in-law and his wife and children, and so on, or the obstacles that are from the rest of the world, who make fun of him and incite him and obstruct from the Service of Hashem. And he needs to not sense and look at them at all, [rather] only be as the concept: One Was Abraham – as if it is just he in the world as mentioned above.