In פרשת מטות we learn of the request of the two and a half tribes of ראובן גד וחצי מנשה. They requested that they not enter Eretz Yisrael and remain on the other side of the Jordan.
Moshe was devastated at first upon hearing of their intentions. He understood how important keeping up the morale of the people was.
Moshe had still not recovered from the damage done by the spies. They epitomized what it was to hurt the morale. The hopes of entering the Promised Land were shattered when the spies said that it was a land that devours its inhabitants.
The lesson here is to remind us the power that words have. We must never shatter people’s dreams by discouraging them and telling them they will not succeed. This is true on a personal level as well as on a national level. We must always remain positive and optimistic and put our trust in Hashem.