The first five books of the Bible--Genesis, Exodus, Leviticus, Numbers, and Deuteronomy--are collectively called the Pentateuch. Sometimes they are also called the "Five Books of Moses" and there is a very old tradition that claims Moses was their author. This is highly unlikely if not impossible. Still, there are believers who defend the notion.
Scholars tell us that the Pentateuch is actually a composite document, compiled from several sources, and edited long ago into a single narrative. Critical scholarship has developed a highly refined theory of the sources behind the Pentateuch. If you are interested in the details, google "Documentary Hypothesis." As always, read with discernment. There is some good information out there. There is also some crap.
From time to time I come across a claim to the effect that the Documentary Hypothesis has been refuted, discredited, or abandoned by mainstream scholarship. This is not true. I have not seen a refutation of the Documentary Hypothesis that held up to critical scrutiny. Those who say that the hypothesis has been discredited are the Fundamentalists, bibilicists, and inerrantists who, for theological reasons, never gave it any credit to begin with. As for the Documentary Hypothesis being abandoned, I will say that there are schools of criticism that look at the Pentateuch as a finished literary whole. They are not interested in the sources behind the text so much as the text itself. This hardly means that they have abandoned the Documentary Hypothesis. It is just that their interests lie elsewhere.
When a text is woven together from diverse sources it is almost bound to contain repetitions, inconsistencies, and perhaps even contradictions.
Chapter 9 tells how the Israelites celebrated the first Passover outside of Egypt. A provision is made for those who, for reasons of ritual uncleanness or travel, cannot join in the celebration. Their Passover will be held one month later. Exceptions like this reveal a certain grace. The Law is not meant to be a burden.
Numbers 9:14 commands foreigners living among the Israelites to participate in the Passover. In Exodus 12:48 there was a commandment that foreigners who wanted to eat the Passover had to be circumcised. This is not exactly a contradiction, but it does pose a difficulty. What of the uncircumcised foreigner among the Israelites?
Verses 15 ff. concern the pillar of cloud and fire, symbolizing YHWH's presence, which leads the Israelites through the wilderness.
Chapter 10 describes the construction and use of a pair of silver trumpets which are used to signal various kinds of information to the Israelites.Verses 11-28 describe the Israelites departure from Sinai and the order in which the tribes march.
Then, in verses 29 ff. we find Moses in conference with his father-in-law. In Exodus 2, the man was called Reuel. In Exodus 18, he was known as Jethro. Here he is called Hobab, son of Reuel. Granting that Reuel might be a clan or tribal name, and granting that a lot of biblical characters (and places) are known by more than one name, there is no real problem here. I would venture a guess that the various names of Moses' father-in-law come from different sources. The fact that Jethro is said to have gone back to his home back at Exodus 18:27, and there is no mention of his return to the Israelite camp, and yet here he is as Hobab being invited to travel with the Israelites....Let's just call it a continuity mistake.
I'm not entirely sure whether Moses persuaded his father-in-law to travel along or not.
Numbers 10 concludes with the "Song of the Ark." This consists of two sets of verses, one for departure and one for arrival, which describe YHWH as a warrior.
Next: Numbers 11-13