As part of Moshe’s final speech, introducing the תוחכה, he says:
Rashi makes the point that היום הזה doens’t mean literally “today”; it means “every day”:
But I want to focus on the expression את ה׳ האמרת היום. What does הֶאֱמַר mean?
Rashi is apparently contradicting himself; first he says there is no עד, no other example, for האמר, so he speculates that it means a pledge of exclusivity. Then he says there is an עד, and it means “glorify”, which isn’t exactly the same thing. The answer seems to be that the manuscripts of Rashi’s commentary and some of the original printed versions don’t include the bracketed text (which is why Artscroll, for instance, brackets it). It seems that Rashi himself didn’t know of any other use of האמר, but that the editor found another soure in ספר תהילים.
But that’s a weird thing to say. Didn’t Rashi know about that pasuk? It’s the שיר של יום for Wednesday! And Rashi himself translates האמרת with reference to that pasuk when it is discussed in the gemara:
So I would assume that Rashi knew full well about יִתְאַמְּרוּ כׇּל פֹּעֲלֵי אָוֶן but didn’t want to translate our psukim that way in his Chumash commentary. He wanted to make another point.
Ramban connects הֶאֱמַר to a similar word earlier in the ספר:
If it is a loan word, then it is not surprising that the spelling would vary. I suspect that it is the same as the English “emir”, from the Arabic for “commander”. Spelling varies for loan words (as crossword solvers know—”emir“ can be “emeer”, “amir” or other variants!). So האמרת means “you have made Him commander”. And that meaning is apparently consistent with the context: ה׳ has power over others: לשמע בקלו, and Israel has power over others: לתתך עליון על כל הגוים.
Rashi’s reading of האמרת as לשון הפרשה והבדלה, which Artscroll translates as “distinguish”, comes from the gemara:
The message of האמר is not of power but of exclusivity.
This paragraph is the equivalent of קידושין. We are pledged to each other. And that is what תפילין is a symbol of:
And that commitment is mutual. Atkins says that is what monotheism really means:
את ה׳ האמרת היום and ה׳ האמירך היום tells us that the relationship is mutual. The commitment goes in both directions.
Rashi’s point, I think, is that this paragraph is all about היום, ”today“, in the sense of “everyday”. We go back to היום הזה ה׳, את ה׳ האמרת היום, וה׳ האמירך היום: בכל יום יהיו בעיניך חדשים. And that tells us how to look at the תוחכה:
When we put on תפילין we recite the lines from הושע:
Everyone asks, why do we want to be “engaged” forever? Shouldn’t the engagement end, and we get to the נישואין?
ה׳ האמירך היום להיות לו לעם סגלה is G-d’s way of saying הרי את מקודשת לי.