Another theme of פרשת שלח is the danger of speaking לשון הרע. Chazal say that although בני ישראל tested Hashem ten times, it was the לשון הרע that they spoke, that sealed their fate. Because of this particular sin, they were prevented from being able to enter Eretz Yisrael.
It is also written in the Gemara in ערכין: “Come and see how great is the sin of לשון הרע. If the מרגלים, who brought a bad name on wood and stone, where the Torah says they spoke badly about the Land, one who brings a bad name on his friend, how much more is this damaging!”
It is a good idea to be reminded from time to time that we pay attention to what we say. Words can be damaging and we cannot take them back.
This lesson is to be learned from Miriam as well as from the spies. Speech is a gift that we must not abuse.