Once when Rabbi Shneur Zalman of Lyady, the author of the Tanya, was in Mezhirech and served the Maggid, his teacher summoned him and said to him, "There is an indictment against Israel in Heaven, because the poskim [deciders of Jewish law] and the Kabbalists do not agree concerning the shape of the letters in Tefillin, Torah scrolls, and Mezuzot." He accordingly ordered Rabbi Shneur Zalman to thoroughly study the writings of the poskim and the Kabbalists, to find a way of writing that would be acceptable to both. Rabbi Shneur Zalman assumed the burden of this holy task, and some time later he drew the shapes of the letters in a manner that conformed with both opinions. When he brought the sketches to his holy teacher and rabbi, the Maggid gazed directly upon him, thanked him for his work, and told him that at that moment the Heavenly entourage declared that this was the correct shape of the letters.
The following day Rabbi Shneur Zalman went on his way, taking his leave of the Maggid with a blessing for the way from his teacher. His journey took him through the city of Anapol. He arrived there at night, with the entire city asleep. Rabbi Shneur Zalman saw from afar a single house in which a candle was burning, and he went there to spend the night. This house was that of Reb David, a scribe. When Rabbi Shneur Zalman entered the house, he found Reb David sitting and writing a Torah scroll, and he did not want to disturb the scribe. He walked silently until he came to where the scribe was writing. To his great surprise, he saw that Reb David was writing the letters just as he had sketched them yesterday for the first time, after much time and effort. Rabbi Shneur Zalman was greatly amazed, because he knew that Reb David had not been in Mezhirech when he gave his sketches to the Maggid. He waited until the scribe finished writing. Reb David was very happy to see Rabbi Shneur Zalman, and he received him with great affection and honor. The rabbi asked him where he had learned this method of writing the letters. Reb David replied: "I myself know nothing, but the holy rabbi Zusha told me today that the Heavenly entourage declared that the letters were to be written in this shape, that corresponds to the opinions of both the poskim and the Kabbalists. And Rabbi Zusha drew for me in detail how to write." In great trepidation because of Rabbi Zusha`s holiness, Rabbi Shneur Zalman went to meet the great rabbi, before continuing on his journey.