Numbers 10:10-11

10“Also in the time when you rejoice, such as on your appointed festivals or at the beginnings of your months, you must blow with your trumpets over your burnt offerings and over the sacrifices of your peace offerings, so that they may become a memorial for you before your God: I am the Lord your God.”

11On the twentieth day of the second month, in the second year, the cloud was taken up from the tabernacle of the testimony.