Мидраш к Бамидбар 19:4

"Command": The command is immediately, for present performance and for future generations. You say thus, but perhaps it is only for future performance! It is, therefore, (to negate this) written "Command the children of Israel that they send … (Bamidbar 19:4) "And the children of Israel did so, sending them outside the camp" — whence we derive that the command is for immediate performance. And whence do we derive that it is (also) for future generations? From (Vayikra 24:2) "Command the children of Israel that they take to you clear olive oil … (3) … an eternal statute for your generations." — But how do we derive (the same) for all the commands in the Torah? R. Yishmael says: Since we find unqualified commands in the Torah, and one of them was qualified as being for present performance and for future generations, we derive the same for all the mitzvoth in the Torah. R. Yehudah b. Bethira says: "command" in all places connotes impulsion (to the act), as it is written (Devarim 3:28) "And command Joshua and strengthen him and fortify him" — whence we learn "We strengthen only the (internally) strengthened," and "We impel only the (internally) impelled." R. Shimon b. Yochai says: "Command" in all places entails expense, as it is written (Vayikra 24:2) "Command the children of Israel that they take to you pure olive oil," (Bamidbar 35:2) "Command the children of Israel that they give to the Levites from the inheritance, etc." (Bamidbar 28:2) "Command the children of Israel and say to them: My offering, My bread, for My fires" — whence we see that "command" in all places entails expense. Except in one; and which is that? (Bamidbar 34:2) "Command the children of Israel and say to them: When you come to the land of Canaan, etc." — where the intent is: Impel them to the division of the land. Rebbi says: "Command" in all places is exhortation, as it is written (Bereshit 2:16-17) "And the L-rd G-d commanded (i.e., exhorted) the man, saying … but of the tree of knowledge of good and evil, you shall not eat."