In the third aliyah, Calev and Yehoshua, who both began speaking near the end of the second aliyah, continue speaking in this aliyah and beg the people to trust in G-d to bring them to the land flowing with milk and honey. Furthermore, they beg the people to not rebel against G-d and Moshe. But the Jewish people reject their plea and decide to stone them.
G-d then appears in a cloud and asks Moshe how long will these people despise G-d and not believe in all the miracles G-d has done for them. G-d says he will destroy the people and raise a new nation mightier than them. But Moshe points out that it won't look good to the Egyptians that G-d took the Jewish people out of Egypt only to kill them in the desert.
Moshe begs for G-d's mercy. G-d then decides that this generation will wander in the desert for forty years (one year for each day the spies traveled). All this generation, except for Calev and Yehoshua, will die in the desert and not enter into the Promised Land. That is their punishment for believing the loshen hora of the spies and not trusting in G-d.