1)
Is this verse a command?
1.
Radak: No, it is the condition (continuation of verse 9). If you will heed Me, and there will be no foreign god among you in which you will trust, and you will not bow to another god, and you will remember that I raised you from Egypt... (refer to 81:11:3:1).
2.
Malbim: No, it is a warning. If you will serve idolatry, rain will not come in its time - "Pen Yifteh Levavchem v'Sartem va'Avadtem Elohim Acherim; ...v'Atzar Es ha'Shamayim v'Lo Yihyeh Matar" (Devarim 11:16-17). If you will heed Me, and there will be no foreign god among you, "Harchev Picha va'Amal'ehu" (verse 11).
