וַיְצַ֣ו יְהוֹשֻׁ֔עַ אֶת־שֹׁטְרֵ֥י הָעָ֖ם לֵאמֹֽר׃
Josua gebot alsdann den Beamten des Volkes also:
Rashi on Joshua
And Yehoshua commanded. He did this on the day that completed the days of mourning for Moshe.19Moshe died on the seventh day of Adar and he was mourned for thirty days. See Devorim 34:8.