On Rosh Hashanah of the year 5507, Reb Yisrael – commonly known as the Baal Shem Tov – went up to Heaven to see what was happening there. The things he saw there were so incredible that they are simply impossible to explain.
On his way back to Earth, the Baal Shem Tov stopped off in Gan-Eden-Hatachton, (the lowest of the seven Gan-Eden’s), where he met many different types of souls. The souls immediately recognized the great Tzaddik, and together as one they begged him to please help them reach higher places in Heaven. Reb Yisrael saw how happy they were that he had come and how certain they were that he would help them and go up with them to higher places – therefore he agreed to do it. However, since Reb Yisrael had never gone so high before, he was afraid that he might be unable to come all the way down again; he therefore asked his Rebbe, Achiya Hashilony, to come with him, for Reb Yisrael felt safer with his teacher at his side. (Achiya Hashilony was a prophet who had lived from the times of ancient Egypt all the way to the times of King Shlomo; although he had already passed away, he would come to the Baal Shem Tov to teach him Torah.)
The Baal Shem Tov, Achiya Hashilony and the souls then began to soar up high into Heaven. They went highand higher, coming to places so high in fact, that even Reb Yisrael himself had never been to them before. They came to an incredibly high place and there, before their eyes, stood the heavenly palace of Moshiach, which is where Moshiach learns Torah with all the Tannaim and Tzaddikim who have already passed away.
Reb Yisrael entered the palace and saw that everyone there was very happy about something. He wasn’t sure about what but was afraid that maybe it was because he had died, and that’s why the Tzaddikim were so happy – because he had come to join them. However, they reassured him that his time to leave the world had not yet come.
Reb Yisrael then asked Moshiach, “When are you coming, Master?”
“When your teachings will spread to the rest of the world!” Moshiach answered.
Upon hearing those words the holy Baal Shem Tov immediately returned to Earth and spread his teachings far and wide, in greater amounts and to more people than he had ever done before.
Taken from: https://www.torah4blind.org/children/zk-4.htm