וַיֵּ֨רֶד יְהוָ֥ה ׀ בֶּעָנָן֮ וַיְדַבֵּ֣ר אֵלָיו֒ וַיָּ֗אצֶל מִן־הָר֙וּחַ֙ אֲשֶׁ֣ר עָלָ֔יו וַיִּתֵּ֕ן עַל־שִׁבְעִ֥ים אִ֖ישׁ הַזְּקֵנִ֑ים וַיְהִ֗י כְּנ֤וֹחַ עֲלֵיהֶם֙ הָר֔וּחַ וַיִּֽתְנַבְּא֖וּ וְלֹ֥א יָסָֽפוּ׃
Yang Mahakekal turun dalam awan dan berfirman kepadanya. Ia mengambil sebagian dari roh yang ada padanya dan menaruhnya pada ketujuh puluh tua-tua itu. Ketika roh itu hinggap pada mereka, mereka bernubuat, tetapi sesudah itu mereka tidak bernubuat lagi.
Rashi
ולא יספו [AND THEY PROPHESIED] BUT DID NOT CONTINUE (to prophesy) — i. e. they prophesied only that day alone. Thus is the phrase explained in Siphre. Onkelos, however, rendered renders it ולא פסקין “and they did not cease”, meaning that the gift of prophecy never again departed from them (cf. Sanhedrin 17a and Rashi on Deuteronomy 5:19).
Or HaChaim
וירד ה׳ בענן וידבר אליו, G'd descended within the cloud and spoke to him, etc. What did G'd say to Moses? Besides, what was the neeed for this whole procedure? Why did G'd not simply let these people prophesy? We may understand what happened when we consider a statement of the Zohar on Pinchas 220 on Numbers 25,12: "Behold I give unto him My covenant, peace." G'd commanded Moses to bestow this covenant of peace on Pinchas. The reason was that Moses had already acquired that gift so that it was considered his possession. Seeing that G'd does not take away a gift He had given to someone in order to give it to someone else, Moses had to be the one to bestow it on Pinchas. Similarly, here. Moses had been given the gift of prophecy, exclusively. When G'd wanted to give the elders the gift of prophecy He had to do so via Moses. This is why Moses is known as אדון הנביאים, the "master" of the prophets. When Moses assembled the elders he remained with them and G'd descended within the cloud. The word vayedaber may be read as vayadber, "He made subordinate" (compare Psalms 47,4). G'd took permission from Moses to transfer some of his Holy Spirit.
Rabbeinu Bahya
וירד ה' בענן וידבר אליו ויאצל מן הרוח אשר עליו ויתן על שבעים איש הזקנים, “G’d descended in a cloud and spoke to him, and He increased some of the spirit that was upon him and gave it to the seventy men, the elders.” Rabbi Avraham Ibn Ezra writes that Moses took six men from each tribe, a total of 72. Since G’d had told him to take 70 men, two of them were left out. This is correct. Thus far the wording of Ibn Ezra.