“Then the glory of Yahweh appeared at the tent of meeting to all the Israelites.  Yahweh said to Moses, ‘How long will this people despise me?   How long will they refuse to believe in me, in spite of all the signs which I have done among them?  I will strike them with pestilence and disinherit them.  I will make of you a nation greater and mightier than they.’”

Yahweh does not take kindly to complaints, just like in Exodus, chapter 32.  Then he appeared at the tent of meeting and asked Moses, how long and why should he put up with these people?  Yahweh said that he was going to strike them with pestilence and disinherit them.  He was going to make a great nation out of Moses himself.  Got the message?

“But Moses said to Yahweh, ‘Then the Egyptians will hear of it.  In your might you brought up this people from among them.  They will tell the inhabitants of this land. ‘They have heard that you, O Yahweh, are in the midst of this people.  For you, O Yahweh, are seen face to face, and your cloud stands over them.  You go in front of them, in a pillar of cloud by day and in a pillar of fire by night.  Now if you kill this people all at one time, then the nations who have heard about you will say, `It is because Yahweh was not able to bring this people into the land which he swore to give them that he slaughtered them in the wilderness.’ Now, therefore, let the power of Yahweh be great in the way that you promised, when you spoke, saying: ‘Yahweh is slow to anger,  and abounding in steadfast love, forgiving iniquity and transgression, but by no means clearing the guilty, visiting the iniquity of the parents upon the children, to the third and the fourth generation.’  Forgive the iniquity of this people according to the greatness of your steadfast love, just as you have pardoned this people, from Egypt even until now.’”

But Moses is a great negotiator and interceded with Yahweh as he had done in the Exodus story, chapter 32.  He said that the Egyptians would hear about it and say that Yahweh was not able to bring his people into the land which he swore to give them. Instead he killed them in the wilderness. He reminded Yahweh that his power is great.  Then he recited the liturgical poem that was the same as n Exodus, chapter 34:

Yahweh is slow to anger;

Yahweh abounds in steadfast love;

Yahweh forgives iniquity and transgression;

Yahweh by no means clears the guilty

Yahweh visits the iniquity of the parents upon the children, to the third and the fourth generation.

Moses then asks Yahweh to forgive the iniquity of this people because of the greatness of his steadfast love.