Rashi on TanakhDeuteronomy 8

The entire mitzvah. This can be understood in its plain sense. There is also a Midrashic explanation: If you began to fulfill a mitzvah, complete it; for the mitzvah carries the name only [it is only accredited] of the one who completes it, as it is said, “And the bones of Yoseif which Bnei Yisroel brought up from Egypt they buried in Shechem.” Now, didn’t Moshe himself attend to them [the bones] to bring them [up from Egypt]? However, since he had no opportunity to complete it, and Bnei Yisroel did complete it, it is called by their name.

Will you guard His mitzvos — not to test Him and not to be critical of Him.

Your garment did not wear out on you. The clouds of Divine Glory rubbed the grime off their clothes and pressed them like pressed garments; and their children too, as they grew, their clothes grew with them, similar to the covering (shell) of a snail which grows with it.

Nor did . . . swell. It did not blow up like dough (בָּצֵק). This usually happens to those who walk barefoot, that their feet become swollen.

זֵית שֶׁמֶן — (literally, the olive of oil). Its meaning is, olives that produce oil.