Kommentar zu Dewarim 31:13

ובניהם אשר לא ידעו, seeing that due to their tender age they are unable to formulate their questions if they have any.

ובניהם אשר לא ידעו, "and their children, who do not know, etc." This division is in line with mention of "and the children" in verse 12 as part of the מצוה of הקהל. Moses says that although he is aware that the children are too young to understand what they would hear at that assembly, they are not too young to learn to fear G'd, i.e. one must train them in יראת השם from an early age.

ובניהם אשר לא ידעו ישמעו ולמדו ליראה, “and their children who do not know of this will learn and be in awe, etc.;” when they will hear about it and ask their parents who will instruct them in all aspects of Judaism and Jewish history. The word טף, frequently used to describes babies, in this case speaks of children that are already older and that can be taught. In the previous verse the Torah wrote:ילמדו ויראו, ”they will learn and be in awe,” instead of “they will learn to be in awe.” Our sages do not understand the word טף here as referring to children of school-going age, but to infants, and they explain that the reasons that the mothers were to bring them along was to receive a reward for their efforts.

AND THAT THEIR CHILDREN, WHO HAVE NOT KNOWN, MAY HEAR, AND LEARN TO FEAR. This refers to the little children [mentioned in the preceding verse], for they will hear and inquire, and the fathers will accustom them [to the words of the Law] and educate them. For the little children [mentioned here] are not those who suckle at the breasts, but rather the young in years who are nearly old enough to be educated, this being the sense of the expression and learn to fear — in the future [when they are grown up]. But above [when speaking of the men and the women] he stated, that they may learn, and fear¹³Verse 12. [now, since they are adults]. However, our Rabbis have said,¹⁴Chagigah 3a. “The men came to learn, and the women to listen. And the little children — why did they come? In order to reward those who bring them.”¹⁵From this text it appears that the Rabbis understood the term little children as applying to the very young who are not yet old enough to ask questions.

V. 13. ובניהם וגו׳ die Kinder, die noch kein Verständnis haben, durch das, was sie dort aus dem Gesetze hören, zum Studium und zur Erfüllung des Gesetzes zu gelangen, werden doch durch das gemeinsame Anhören des Gesetzes mit den Eltern in der großen allgemeinen Versammlung, schon durch den Eindruck, den die ehrfurchtsvoll aufhorchende Menge auf das Kindesgemüt macht, zur Gottesfurcht gebracht. Bei ihnen sind nicht שמיעה למוד ויראה drei getrennte Momente, sondern ישמעו ולמדו ליראה, durch das Anhören selbst lernen sie Gottesfurcht, שמירה ועשיה liegt ihnen jedoch noch ferne.

ישמעו, either simply that their ears will hear sounds, or, if they are a little older, that they will hear words.

This is the reason why Moses changed the sequence in which he described this process. Whereas in verse 12 he had said ילמדו ויראו they would "learn and (as a result) fear," in this verse he says "they will learn to fear." Being present at such an experience as הקהל is inspirational even for young children and inspires fear of G'd. Moses adds the comment כל הימים, "all the days," to remind us that when fear of G'd is instilled in children at an early age it will last them all their lives.

Nach ח׳׳א ,מהרש׳׳א zu Chagiga 3 a wären בניהם אשר לא ידעו hier קטנים שהגיעו לחינוך Kinder in dem Alter, dem bereits ein Verständnis der תורה, doch noch nicht die Reife der Erfüllungspflicht zugetraut werden könne, weshalb hier wohl von למוד und יראה, aber noch nicht von שמירה לעשות gesprochen wird. Der Begriff טף im vorigen Verse umfasse aber selbst Kinder in noch früherer Altersstufe, weshalb dort in Chagiga die Frage sein konnte: טף למה באין, und die Antwort lautet: ליתן שכר למביאיהן. Bei so kleinen Kindern liegt das Verdienst zunächst in den Großen, die sie mitbringen, und sich damit vor Gott mit ihren teuersten Pfändern um sein Gesetz sammeln, für welches sie einst ihre Kinder gewinnen und damit die Unvergänglichkeit des Gesetzes im jüdischen Kreise sichern sollen und wollen. In 18מס׳ סופרים b ist dem כדי ליתן שכר למביאיהן noch beigefügt: והן לקבל שכר, dass auch für die Kleinen selbst das Mitgehen in die große תורה-Versammlung nicht ohne wohltätigen Eindruck für ihr späteres Leben bliebe. Siehe den Kommentar נחלת יעקב daselbst.

ולמדו, they will ask adults and learn by listening intently to the answers they receive from people who do understand.

Our sages (Chagigah 3) ask why the women had to drag their children along for this assembly, and they answer "in order to receive credit for complying with the instruction." Presumably they referred to those children who could not even appreciate that their elders were listening to the Torah, i.e. the babies in arms. They must have understood that Moses' reason for bringing them applied only to children who were already somewhat older.