וַיֹּ֨אמֶר יְהוָ֜ה אֵלָ֗יו זֹ֤את הָאָ֙רֶץ֙ אֲשֶׁ֣ר נִ֠שְׁבַּעְתִּי לְאַבְרָהָ֨ם לְיִצְחָ֤ק וּֽלְיַעֲקֹב֙ לֵאמֹ֔ר לְזַרְעֲךָ֖ אֶתְּנֶ֑נָּה הֶרְאִיתִ֣יךָ בְעֵינֶ֔יךָ וְשָׁ֖מָּה לֹ֥א תַעֲבֹֽר׃
여호와께서 그에게 이르시되 이는 내가 아브라함과 이삭과 야곱에게 맹세하여 그 후손에게 주리라 한 땅이라 내가 네 눈으로 보게 하였거니와 너는 그리로 건너가지 못하리라 하시매
Rashi on Deuteronomy
לאמר לזרעך אתננה הראיתיך TO SAY, TO THY SEED WILL I GIVE IT, I HAVE LET THEE SEE IT, i.e. in order that you may go and say to Abraham, to Isaac and to Jacob: The oath which the Holy One, blessed be He, swore to you — that oath He has fulfilled. This is the force of לאמר (Berakhot 18b), “to say it”, viz., that you may say it — for that reason have I let you see it. But it is a decree from Me that שמה לא תעבר THERE YOU SHALL NOT CROSS OVER; for were this not so, I would keep you alive even until you saw them planted and settled in it, and you would then go and tell them (the patriarchs).
Sforno on Deuteronomy
הראיתיך בעיניך, in order for you to give it your blessing.
Or HaChaim on Deuteronomy
לאמור לזרעך אתננה, to say: "to your descendants I will give it." The reason the Torah had to write the word לאמור "to say" at this juncture, was that as of now G'd had not given this information to the patriarchs. [In connection with a statement that the dead communicate with one another, Ed.], our sages in Berachot 18 claim that G'd ordered Moses to tell the three patriarchs (after his death) that He had already discharged the oath He had sworn to them to give the land to their descendants. Perhaps the reason G'd wanted Moses to tell the patriarchs [instead of telling them Himself, Ed.] may have been so that Moses would make sure that the patriarchs would appreciate that G'd was able to keep His promise to them only after having overcome many difficulties and setbacks en route.