The discontent of the people because of the hardships of the wilderness journey is more against God than against Moses. But now Moses has got to pay for it as well. It is not so much the people who are revolting, but the leaders. The evil of discontent among the people also affects the leaders.
Miriam and Aaron are annoyed by the fact that Moses has a Cushite, or Ethiopian, woman, referring possibly to Zippora. That their brother hath taken a wife from the Gentiles is a thorn in their eye. They cannot bear the fact that grace is shown to the Gentiles.
In the parable of the vineyard that the Lord Jesus later tells, it appears that the same attitude of intolerance toward the proving of grace to the Gentiles dominates the Jews (Lk 20:1616He will come and destroy these vine-growers and will give the vineyard to others.” When they heard it, they said, “May it never be!”). Even later we see that nothing has changed among the people. When Paul speaks about grace going to the Gentiles, the Jews become fierce (Acts 22:21-2221And He said to me, ‘Go! For I will send you far away to the Gentiles.’”22They listened to him up to this statement, and [then] they raised their voices and said, “Away with such a fellow from the earth, for he should not be allowed to live!”).
Aaron as a person again shows his weak character. He gave in to the will of the people and gave them a golden calf (Exo 32:1-21Now when the people saw that Moses delayed to come down from the mountain, the people assembled about Aaron and said to him, “Come, make us a god who will go before us; as for this Moses, the man who brought us up from the land of Egypt, we do not know what has become of him.”2Aaron said to them, “Tear off the gold rings which are in the ears of your wives, your sons, and your daughters, and bring [them] to me.”). Now his sister, who seems to be taking the initiative, whispers something about Moses to him, he submits again and follows her in her revolt against Moses.
The remark of Miriam and Aaron that God did not only speak through Moses is true. Miriam is called “the prophetess” (Exo 15:2020Miriam the prophetess, Aaron’s sister, took the timbrel in her hand, and all the women went out after her with timbrels and with dancing.) and Aaron is the high priest. They have both a place as a connection between God and the people. Together with Moses they occupy an important position, which is given to them by God. The prophet Micah later points this out to God’s people: “Indeed, I brought you up from the land of Egypt And ransomed you from the house of slavery, And I sent before you Moses, Aaron and Miriam” (Mic 6:44“Indeed, I brought you up from the land of Egypt
And ransomed you from the house of slavery,
And I sent before you Moses, Aaron and Miriam.
). But that should not be a reason to rise to that position or to be jealous of what the Lord has given another. They indicate that they want to be equal to Moses. By having a heathen woman, he has lost his rights, they think, or at least they are on the same level as Moses, they think.
Perhaps Miriam did not say her remarks out loud, but only whispered in Aaron’s ear, but “the LORD heard it”. Our most confidential remarks have a Hearer in Heaven.