Numbers 10:2-3

10:2 “Make two trumpets of silver; you are to make them from a single hammered piece. You will use them for assembling the community and for directing the traveling of the camps. 10:3 When they blow them both, all the community must come to you to the entrance of the tent of meeting.

Numbers 10:10

10:10 “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.”