In Chabad, the saying of a Maamor carries unique significance. The role of a Rebbe is most essentially epitomized in delivering an original Maamor to his Chassidim who would be upstanding because they understand that he is drawing a new light into the world, a new vision for each of them as individuals and for the world as a whole.
During farbrengens, on an understated signal from the Rebbe the Chassidim would be prompted to sing (the Rostover Niggun) a slow and evocative melody. The Rebbe’s facial expression would change and it appeared that his focus turned inward. At a point in the melody, he would close his eyes. When it concluded, he would speak — eyes yet closed — in a distinct sing-song, communicating refined spiritual concepts.
In contrast to his Sichos (“talks”), where the Rebbe looked at his Chassidim and spoke to them, during these discourses, he was not focused on his listeners. Instead, he was absorbed in the ideas and imparted them in the abstract. At that time, many a Chossid would recall our Sages’ words: “The Divine presence spoke from Moshe’s throat.”
Such discourses, called Maamorim, represent a distinct element of the Chassidic tradition. Indeed, in previous generations, this was the primary medium by which the Rebbeim would communicate teachings to their followers. For generations to come they will study the Maamor carefully, striving to comprehend it as much as possible, to repeat it and explain it in their own words, to integrate it into their worldview and into the way they live, and to illuminate all reality with its vision.
(Adapted from Chabad.org)