This is simpler that it appears. See the appendix for a few remarks about Jethro/Reuel.
Now, while Jethro was the priest of Midian (Ex 2:16, 3:1, Num 10:29), the reference in Judges 1:16 is easily misunderstood. It is highly probably that the text is slightly garbled. Note the two solutions to this problem.
Solution #1
Probably the simplest is to make "Hobab" the "brother-in-law" of Moses. Note the comments of Ellicott:
(16) The children of the Kenite, Moses’ father in law.—It is difficult
to disentangle the names Jethro, Reuel, or Raguel, and Hobab (Judges
4:11); but in my article on Jethro in Kitto’s Bible Cyclopœdia I have
shown that Jethro and Reuel are identical, the latter name (“friend of
God”) being his local title as a priest of Midian; and that he was the
father of Zipporah and Hobab. When Jethro refused to stay with the
Israelites (Exodus 18:27), Hobab consented to accompany them as their
hybeer or caravan-guide. He is well known in the Mohammedan legends as
Schocib, but is confounded with Jethro.
The Kenites were the elder branch of the tribe of Midianites. They
lived in the rocky district on the shores of the gulf of Akabah
(Numbers 21:1; Numbers 24:21; 1Samuel 15:6). They seem to have been
named from a chieftain Kain (Genesis 15:19; Numbers 24:22; Heb., where
there is a play on Kenite and Kinneka, “thy rest”). They were
originally a race of troglodytes or cave-dwellers. The Targum
constantly reads Salmaa for Kenite, because the Kenites were
identified with the Kinim of 1Chronicles 2:55. Jethro, they say. was a
Kenite, who gave to Moses a house (Beth) and bread (lehem) (Exodus
2:20-21). They identify Jethro with Salmaa, because in 1Chronicles 2:5
Salma is the father of Bethlehem. They also identify Rechab, the
ancestor of the Rechabites—who were a branch of the Kenites—with
Rechabiah, the son of Moses.
The Cambridge commentary is similar:
- The text of this verse has been badly preserved, and some details of the restoration must remain doubtful.
the children of the Kenite, Moses’ brother in law] Marg. father in
law, as O.T. usage requires. A proper name and the article (inserted
by RV.) have fallen out before Kenite; LXX. cod. B restores Jethro,
cod. A Hobab. The traditions differ as to the name of Moses’ father in
law; in J it is Hobab, Numbers 10:29, cf. ch. Jdg 4:11; in E it is
Jethro, Exodus 3:1; Exodus 4:18; Exodus 18:1. As this chapter is
related to J, the former is preferable: the children of Hobab the
Kenite. The traditions differ again as to the tribe to which Moses’
father in law belonged; here and in Jdg 4:11 he is called a Kenite
(see the note below), but in Exodus 2:15 ff; Exodus 3:1; Exodus 18:1,
Numbers 10:29 he is a Midianite. Common to both traditions is Moses’
connexion by marriage with an Arab tribe. The verb went up in clause a
is plur.; in clause b went and dwelt are sing., and may be corrected
to the plur. (with RV., LXX. B they dwelt). But the sing, verbs in
clause b perhaps imply that the text originally ran And Hobab the
Kenite … went up (sing.) … and went and dwelt, omitting the children
of.
The Pulpit Commentary appears to agree
Verse 16. - The children of the Kenite, etc. It appears from this
verse that the invitation given by Moses to his "father-in-law," or
rather "brother-in-law," Hobab, to accompany him and the Israelites to
the land of promise, though at first rejected (Numbers 10:29, 30), was
eventually accepted. Hobab and his tribe, a branch of the Midianites,
called Kenites, from an unknown ancestor, Kain, at first settled in
the city of palm trees, i.e. Jericho (Deuteronomy 34:3); but it seems
that when Judah started on his expedition with Simeon to conquer the
south laud, the Kenites went with him. A subsequent migration of a
portion of this nomadic tribe is mentioned (Judges 4:11). Dwelt among
the people, i.e. the people of Judah. For Arad see Numbers 21:1.
Judges 1:16
Solution #2
This idea is provided by Benson:
Jdg 1:16. The children of the Kenite — Jethro, Moses’s father-in-law,
seems to have been called a Kenite from the people from whom he was
descended, Numbers 24:21-22. His posterity, it appears, came into
Canaan with the Israelites, and were settled there with them. Went up
from the city of palm-trees — That is, from Jericho, so called,
Deuteronomy 34:3; not indeed the city, which had been destroyed; but
the territory belonging to it, where, it seems, they were seated in a
most pleasant, fruitful, and safe place, according to the promise made
by Moses to their father, Numbers 10:31-32; and whence they might
remove either to avoid the neighbouring Canaanites, or out of love to
the children of Judah. In the south of Arad — The southern part of the
land of Canaan, where Arad was, Numbers 21:1. And dwelt among the
people — Hebrew, that people; namely, those children of Judah that
lived there.
Matthew Poole is similar:
Children of the Kenite, i.e. of Jethro, so called from the people from
whom he descended, Numbers 24:21,22. And whatsoever he did, it is
evident that his posterity came into Canaan with the Israelites, and
were there seated with them. See Judges 4:11,17 5:24 1 Samuel 15:6 1
Chronicles 2:55.
APPENDIX - Jethro/Reuel
Moses' father-in-law was known by two names:
- Reuel; This was probably his birth names and means "friend of God". It is used in several places, Ex 2:18, 21, Num 10:29
- Jethro; This was probably a title as it means "excellency". It is used in Ex 3:1, 4:18, 18:1, 2, 5, 6, 9, 10, 12.
In the case of Judges 4:11 which calls "Hobab the father in law of Moses" is an obvious mistranslation. It should be "brother-in-law" as Ellicott observes:
(Judges 4:11) The father in law of Moses.—Rather, the
brother-in-law. The names for these relationships are closely allied.
(See Note on Judges 1:16.)