What is the purpose of the word וְהָיָ֗ה in Devarim 11:13?

Question

Deuteronomy 11:13 says:

וְהָיָ֗ה אִם־שָׁמֹ֤עַ תִּשְׁמְעוּ֙ אֶל־מִצְוֺתַ֔י אֲשֶׁ֧ר אָנֹכִ֛י מְצַוֶּ֥ה אֶתְכֶ֖ם הַיּ֑וֹם לְאַהֲבָ֞ה אֶת־יְהוָ֤ה אֱלֹֽהֵיכֶם֙ וּלְעָבְד֔וֹ בְּכָל־לְבַבְכֶ֖ם וּבְכָל־נַפְשְׁכֶֽם׃

And it shall be that if you will listen to My commandments which I command you this day, to love the LORD your God, and to serve Him with all your heart and with all your soul.

The word וְהָיָ֗ה seems extra. The verses that follow make it seem quite obvious that if you obey the commandments, you will receive a reward. The reward comes in the future, after performing the commandments. What then, is the purpose of the word וְהָיָ֗ה in this verse?

Answer 1

The Daat Mikra commentary on Isaiah 2:2 indicates that the word והיה is an introductory word indicating that the following relates to the future.

והיה – הדבר עתיד לבוא. 'והיה' פותחת תאור מה שיהיה בעתיד. כדרף ש'ויהי' פותחת תאור מה שהיה בעבר. והוי"ו של 'והיה' אינה לחבור אלא לפתיחה.

והיה — This matter is in the future. The word 'והיה' starts the description of something in the future, just as 'ויהי' starts the description of something in the past. And the ו (vav) of 'והיה' is not connective [ie. does not relate to what comes before it], but comes to start [the paragraph].

See also Radak to Joshua 1:1 and ibn Janah's Sefer HaRiqma (ten lines from the bottom). The Daat Mikra commentary on Deuteronomy 6:10, which also starts with והיה, also says that it is an introductory word about a future occurrence, but it adds that the word denotes a promissory note, that part of its purpose is "to show that for sure the matter will be thus" (להודיע שודאי יהיה הדבר כן).

Alternatively, Rashi on Deuteronomy 11:13 says that והיה relates to verse 11, viz. that the land will drink rain from the heavens (ie. it will rain properly), as if to say: "And that which I mentioned will be true, if..."

והיה אם שמוע – 'והיה' מוסב על האמור למעלה: למטר השמים תשתה־מים.

והיה אם שמוע — The word 'והיה' is informed by what is written above: the land will drink rain from the heavens.

Answer 2

Rashi actually addresses וְהָיָה being seemingly extraneous:

(Sources Courtesy of Sefaria)

והיה אם שמע. והיה, מוסב על האמור למעלה, (פסוק יא) למטר השמים תשתה מים:

AND IT SHALL COME TO PASS IF YE WILL HEARKEN — The word והיה is to be connected with what is said above (v. 11): “it drinketh water of the rain of heaven”.

And expounds:

והיה אם שמע תשמעו. אם שמע בישן תשמעו בחדש וכן (דברים ח, יט) והיה אם שכח תשכח, אם התחלת לשכח, סופך שתשכח כלה, שכן כתיב במגלה אם תעזבני יום, יומים אעזבך [ במגילת חסידים ] (ספרי מח)

AND IT WILL COME TO PASS IF HEARKENING YE WILL HEARKEN — If you hearken to the old (if you hear again what you have already learnt, i.e. if you repeatedly study the old lessons), you will hearken to the new (you will the more easily gain new knowledge) (Sukkah 46b; cf. Rashi on Exodus 19:5). Similar is the meaning of אם שכח תשכח (Deuteronomy 8:19): If you have begun to forget, your end will be that you will forget all of it. So, too, is written in a certain Scroll: If thou forgettest Me one day, I will forget thee two days (cf. Siphre on v. 22; Jerusalem Talmud end of Berachoth).

Additionally the Ohr HaChaim HaKadosh expounds on what וְהָיָה is coming to add. (Partial Quote)

והיה אם שמוע וגו'. פירוש והיה לשון שמחה ותנאי הוא הדבר אם תהיה שמחה של מצוה

AND IT WILL BE IF YOU WILL LISTEN ETC- וְהָיָה connotes joy and it is a condition (that the following blessing will come) if you have joy of Mitzva (observance)

Hope this can be helpful.

Answer 3

I recall a teacher in high school explaining that VeHayah comes to portend a positive passage; whereas VeYehi is the opposite. Hence this is good - and describes the reward for keeping the mitzvot. The letters are also the same as those in G-d's name, Yud-Key-Vav-Key.

Vayehi starts off Megillat Esther, at whose beginning we hear about evil decrees upon the Jews.

That said, I also recall a discussion in the Talmud, perhaps involved Rav and Shmuel (?), around these two similar words with proofs that neither word is always used to portend good or evil, but that the context matters a lot. The conclusion was not to assume that one word or the other indicates conclusively the nature of what follows, as I recall. My memory may be faulty though... more learned commenters here can perhaps provide the source for easy review?

More broadly, it seems to indicate certainty that the Jews will keep the commandments - as you said, it's a tense that indicates something that happened.

Also, the mystical import of G's name written that way - if you learn Kabbalah and the meaning of G's various names - would probably elucidate your question a lot.