Ibn Ezra on Numbers 10:10

וביום שמחתכם ובמועדיכם. ששבתם מארץ אויב או נצחתם האויב הבא עליכם. וקבעתם יום שמחה כימי פורים ושבעת ימי חזקי"ה (ס"א חנוכה) שמחה. רק המעתיקים פירשו וביום שמחתכם שבת והתקיעה שישמעו ישראל וידעו כי העולות יקריבו ויכונו לבם לשם: ALSO IN THE DAY OF YOUR GLADNESS, AND IN YOUR APPOINTED SEASONS. When you return from the land of your enemies, or you defeat the enemy who attacks you²²In your own land. and you establish a day of rejoicing, such as the days of Purim or the seven days of rejoicing in the days of Hezekiah.²³See II Chron. 30:23. Some manuscripts read Chanukah. In this case, the text should be emended to read, the eight days of Chanukah (Krinsky). However, our transmitters of tradition explained that the day of your gladness refers to the Sabbath.²⁴See Sifre on this verse. The trumpets were sounded²⁵Over the burnt offerings and sacrifices. so that Israel would hear that the burnt offerings were being offered and that they should direct their hearts to God.