כל המצוה — Explain this in its plain sense: EVERY COMMANDMENT. — And a Midrashic explanation is (taking it to mean, “the whole of the commandment … shall ye be heedful to do”): If thou hast once made a beginning with a meritorious deed, carry it out to the end, because it bears the name only of him (it is attributed only to him) who does the last part of it, as it is said, (Joshua 24:32) "And the bones of Joseph which the children of Israel brought up from Egypt they buried in Shechem”. But did not Moses alone busy himself with them to bring them up (cf. Exodus 13:19)? But because he had no opportunity to complete this (to inter them), the children of Israel completed it, it was called by their name (Midrash Tanchuma, Eikev 6).

התשמר מצותו [THAT HE MIGHT KNOW WHAT WAS IN THY HEART] WHETHER THOU WOULDST KEEP HIS COMMANDMENTS — viz., the commandment that ye should not put Him to the test, and that you should not doubt Him (i.e. His ways).

שמלתך לא בלתה THY RAIMENT DID NOT WEAR OUT — the clouds of Divine Glory used to rub the dirt off their clothes and bleach them so that they looked like new white articles, and also, their children, as they grew, their clothes grew with them, just like the clothes (shell) of a snail which grows with it (cf. Shir HaShirim Rabbah 4:11; Yalkut Shimoni on Torah 850).

לא בצקה This means: [AND THY FOOT] DID NOT SWELL like dough (בצק), as is usual with those who walk barefoot — that their feet become swollen.

זית שמן (lit., the olive of oil) means, olives that produce oil (i.e. good olives, not hard fruits that give no oil).