Rashi on Numbers 26:9/רש"י על במדבר כ״ו:ט׳

1אשר הצו WHO INCITED — i.e., who incited Israel, על משה AGAINST MOSES,

2בהצתם WHEN THEY INCITED the people AGAINST THE LORD.

3הצו means they persuaded Israel to strive against Moses — it is a grammatical form denoting “they caused someone to do something".