(16:9) "And Moses said to Aaron: Say to the entire congregation of the children of Israel: Draw near before the L–rd": R. Yehoshua says: (The intent is) draw near to (the place of) G–d's revelation (i.e., to the place where the cloud will descend). R. Elazar says: (The intent is) draw near to render an accounting (for your complaints). (16:10) "And it was, as Aaron spoke, etc.": What is the intent of this? We are hereby apprised that at the very time Aaron spoke this, so it transpired.
Moses Tells Aaron to Gather Israel for Manna
Mekhilta Tractate Vayassa 3:13