"And the people shouted, and they blew with the shofars" (Joshua 6:20). This teaches that they did not have the trumpets that Moses made, for those were hidden away, as it is said, "Make for yourself two silver trumpets" (Numbers 10:2): for you do you make them, and they are entrusted to your hand, and not to Joshua your disciple. And they were hidden away even during the lifetime of Moses, as it is said, "Assemble to me all the heads of your tribes and your officers" (Deuteronomy 31:28), and the trumpets, where were they? They were hidden away, to fulfill what is said, "There is no authority over the day of death" (Ecclesiastes 8:8).
The Silver Trumpets of Moses That Were Hidden Away at His Death
Yalkut Shimoni on Nach 15:20
ויריעו העם ויתקעו בשופרות (יהושע ו, כ). מלמד שלא היה להם חצוצרות שעשה משה שנגנזו שנאמר עשה לך שתי חצוצרות, לך אתה עושה ומסורים בידך ולא ליהושע תלמידך, ואף בחייו של משה נגנזו שנאמר הקהילו אלי כל ראשי שבטיכם ושוטריכם והחצוצרות היכן היו נגנזו לקיים מה שנאמר אין שלטון ביום המות (קהלת ח, ח):