Num

Num 20:12

GOD said to Moses and Aaron, "Because you didn't trust me, didn't treat me with holy reverence in front of the People of Israel, you two aren't going to lead this company into the land that I am giving them."  

You should be able to see how serious this is!  Moses and Aaron were VERY good and humble people but when they crossed God, He did punish them-there’s  no one reading this that’s better than Moses and Aaron and even they were punished by God!