Why did moshe the beadle tell people on his return from being deported?

Moshe the Beadle appears in chapter one in Elie Wiesel's book 'Night'.

He tells a story of his deportation into Nazi Poland. In 1941 the Hungarian government expelled Jews who could not prove their citizenship. Moshe was sent as a foreign Jew to Galicia, in southern Poland.

First, he and many other Jews were crammed onto a cattle train and transported to Poland. The journey itself cost many their lives as food was non-available and many people fell ill. The dead bodies were just left among the living on the train. Once on Nazi territory, the Jews were packed into trucks and driven to a forest, where they were forced to dig pits which then became their own graves. After finishing the digging, each prisoner had to stand in front of the pit where he was shot. Beadle describes the macabre ways the Nazis dealt with babies: they were tossing them in the air and using them as target practice for their guns. Some babies were violently dismembered and left to die. Moshe remembers Malka, the young girl, who took three days to die. He himself survived because he was shot in the leg and was believed to be dead.

Moshe felt like he was saved to warn others about the Nazis. Moshe told the people how the foreign Jews were shot and dumped into large mass graves. However how hard Moseh tried to share his experience, the sighet people didn't believe him.