וַיֹּאמֶר מֹשֶׁה, לְחֹבָב בֶּן-רְעוּאֵל הַמִּדְיָנִי חֹתֵן מֹשֶׁה, נֹסְעִים אֲנַחְנוּ אֶל-הַמָּקוֹם אֲשֶׁר אָמַר ה, אֹתוֹ אֶתֵּן לָכֶם; לְכָה אִתָּנוּ וְהֵטַבְנוּ לָךְ, כִּי-ה דִּבֶּר-טוֹב עַל-יִשְׂרָאֵל.
וַיֹּאמֶר אֵלָיו, לֹא אֵלֵךְ: כִּי אִם-אֶל-אַרְצִי וְאֶל-מוֹלַדְתִּי, אֵלֵךְ.
וַיֹּאמֶר, אַל-נָא תַּעֲזֹב אֹתָנוּ: כִּי עַל-כֵּן יָדַעְתָּ, חֲנֹתֵנוּ בַּמִּדְבָּר, וְהָיִיתָ לָּנוּ, לְעֵינָיִם.
וְהָיָה, כִּי-תֵלֵךְ עִמָּנוּ: וְהָיָה הַטּוֹב הַהוּא, אֲשֶׁר יֵיטִיב ה עִמָּנוּ--וְהֵטַבְנוּ לָךְ.
And Moses said unto Hobab, the son of Reuel the Midianite, Moses' father-in-law: 'We are journeying unto the place of which the LORD said: I will give it you; come thou with us, and we will do thee good; for the LORD hath spoken good concerning Israel.'
And he said unto him: 'I will not go; but I will depart to mine own land, and to my kindred.'
And he said: 'Leave us not, I pray thee; forasmuch as thou knowest how we are to encamp in the wilderness, and thou shalt be to us instead of eyes.
And it shall be, if thou go with us, yea, it shall be, that what good soever the LORD shall do unto us, the same will we do unto thee.'
Who was Chovav? The pasuk states וַיֹּאמֶר מֹשֶׁה, לְחֹבָב בֶּן-רְעוּאֵל הַמִּדְיָנִי חֹתֵן מֹשֶׁה. The question is, does חֹתֵן מֹשֶׁה, typically taken to mean "father-in-law of Moshe," refer to Chovav, or to Reuel? Locally, it can modify either.
However, earlier, we see that Reuel seems to be Moshe's father in law. In Shemot 2:15-22:
וַיִּשְׁמַע פַּרְעֹה אֶת-הַדָּבָר הַזֶּה, וַיְבַקֵּשׁ לַהֲרֹג אֶת-מֹשֶׁה; וַיִּבְרַח מֹשֶׁה מִפְּנֵי פַרְעֹה, וַיֵּשֶׁב בְּאֶרֶץ-מִדְיָן וַיֵּשֶׁב עַל-הַבְּאֵר.
וּלְכֹהֵן מִדְיָן, שֶׁבַע בָּנוֹת; וַתָּבֹאנָה וַתִּדְלֶנָה, וַתְּמַלֶּאנָה אֶת-הָרְהָטִים, לְהַשְׁקוֹת, צֹאן אֲבִיהֶן.
וַיָּבֹאוּ הָרֹעִים, וַיְגָרְשׁוּם; וַיָּקָם מֹשֶׁה וַיּוֹשִׁעָן, וַיַּשְׁקְ אֶת-צֹאנָם.
וַתָּבֹאנָה, אֶל-רְעוּאֵל אֲבִיהֶן; וַיֹּאמֶר, מַדּוּעַ מִהַרְתֶּן בֹּא הַיּוֹם.
וַתֹּאמַרְןָ--אִישׁ מִצְרִי, הִצִּילָנוּ מִיַּד הָרֹעִים; וְגַם-דָּלֹה דָלָה לָנוּ, וַיַּשְׁקְ אֶת-הַצֹּאן.
וַיֹּאמֶר אֶל-בְּנֹתָיו, וְאַיּוֹ; לָמָּה זֶּה עֲזַבְתֶּן אֶת-הָאִישׁ, קִרְאֶן לוֹ וְיֹאכַל לָחֶם.
וַיּוֹאֶל מֹשֶׁה, לָשֶׁבֶת אֶת-הָאִישׁ; וַיִּתֵּן אֶת-צִפֹּרָה בִתּוֹ, לְמֹשֶׁה.
וַתֵּלֶד בֵּן, וַיִּקְרָא אֶת-שְׁמוֹ גֵּרְשֹׁם: כִּי אָמַר--גֵּר הָיִיתִי, בְּאֶרֶץ נָכְרִיָּה.
"Now when Pharaoh heard this thing, he sought to slay Moses. But Moses fled from the face of Pharaoh, and dwelt in the land of Midian; and he sat down by a well.
Now the priest of Midian had seven daughters; and they came and drew water, and filled the troughs to water their father's flock.
And the shepherds came and drove them away; but Moses stood up and helped them, and watered their flock.
And when they came to Reuel their father, he said: 'How is it that ye are come so soon to-day?'
And they said: 'An Egyptian delivered us out of the hand of the shepherds, and moreover he drew water for us, and watered the flock.'
And he said unto his daughters: 'And where is he? Why is it that ye have left the man? call him, that he may eat bread.'
And Moses was content to dwell with the man; and he gave Moses Zipporah his daughter.
And she bore a son, and he called his name Gershom; for he said: 'I have been a stranger in a strange land.'
Thus, Tzippora was Reuel's daughter, which would make the Choten Moshe, the father-in-law of Moshe, Reuel.
However, in Shoftim 4:11
וְחֶבֶר הַקֵּינִי נִפְרָד מִקַּיִן, מִבְּנֵי חֹבָב חֹתֵן מֹשֶׁה; וַיֵּט אָהֳלוֹ, עַד-אֵילוֹן בצענים (בְּצַעֲנַנִּים) אֲשֶׁר אֶת-קֶדֶשׁ.
"Now Heber the Kenite had severed himself from the Kenites, even from the children of Hobab the father-in-law of Moses, and had pitched his tent as far as Elon-bezaanannim, which is by Kedesh."
Thus, Chovav is the Choten Moshe, father-in-law of Moshe. Thus, the pasuk in Bemidbar is somewhat ambiguous, with חֹתֵן מֹשֶׁה, "father in law of Moshe," attaching to either Reuel or Moshe.
To further complicate matters, more famous than either of these two is Yisro, who is generally taken to be Moshe's father in law. The basis of this is two-fold.
First, in Shemot 4:18
וַיֵּלֶךְ מֹשֶׁה וַיָּשָׁב אֶל-יֶתֶר חֹתְנוֹ, וַיֹּאמֶר לוֹ אֵלְכָה נָּא וְאָשׁוּבָה אֶל-אַחַי אֲשֶׁר-בְּמִצְרַיִם, וְאֶרְאֶה, הַעוֹדָם חַיִּים; וַיֹּאמֶר יִתְרוֹ לְמֹשֶׁה, לֵךְ לְשָׁלוֹם.
And Moses went and returned to Jethro his father-in-law, and said unto him: 'Let me go, I pray thee, and return unto my brethren that are in Egypt, and see whether they be yet alive.' And Jethro said to Moses: 'Go in peace.'
So he seems to be staying by Yisro, not Reuel. Further, in parshat Yisro, in Shemot 18 he is referred to multiple times as the Choten Moshe.
וַיִּשְׁמַע יִתְרוֹ כֹהֵן מִדְיָן, חֹתֵן מֹשֶׁה, אֵת כָּל-אֲשֶׁר עָשָׂה אֱלֹהִים לְמֹשֶׁה, וּלְיִשְׂרָאֵל עַמּוֹ: כִּי-הוֹצִיא יְהוָה אֶת-יִשְׂרָאֵל, מִמִּצְרָיִם.
"Now Jethro, the priest of Midian, Moses' father-in-law, heard of all that God had done for Moses, and for Israel His people, how that the LORD had brought Israel out of Egypt."
Further, he is referred to as the priest of Midyan, which was the same term given to Reuel.
How to sort this out?
Some midrashim give Reuel, and/or Chovev, as alternate names for Yisro (among other names - e.g. we have Chever the Kini, so Kini was also a name for Yisro.) I would add - to have some plurality of names is not so far-fetched. After all, we have Avram/Avraham, Sarai/Sara, Yaakov/Yisrael, Yosef/Tzafnat Paneach, whatever Moshe's parents called him/Moshe, Ramses/Pharoah (positional name), Hoshea/Yehoshua (and of course Yitro in one verse is referred to as Yeter/Yitro). And Reuel has flocks and was a priest, so Reu = shepherd + El = of god is not bad as a name assumed when taking a position.
Rashi cites a midrash which explains that Av=father, but people can also call their grandfather father. Thus, the 7 daughters went to their father, that is their grandfather, and told him what happened - how Moshe saved them at the well. Reuel is their grandfather, and thus Chovav is Moshe's father in law, and thus the verse in Shoftim informs us how to parse the pasuk locally in BeMidbar. Rashi immediately beforehand equates Yisro with Chovav, and thus all verses work out. (hmm... perhaps Av as in Bet Av, with Reuel as head of the extended family, the paterfamilias?)
My thoughts on the matter more closely matched that of Ibn Ezra, and I thought I had come up with a groundbreaking pshat until I saw he beat me to it. Basically, Choten need not mean father in law, but can also mean brother in law (I thought in terms of meaning "male in-laws on the wife's side.") Then, Av can mean father, and so Reuel is the father-in-law. Chovav would be a brother-in-law, as would Yisro (if you look carefully at the psukim, none state Yisro's relation to Tzippora). Ibn Ezra also mentions the possibility, that Yisro=Chovev, as they both came to visit Moshe in the Midbar... see inside.
Thus, he dwelled in Midyan, near his brother-in-law Yisro, of whom he took his leave to go to Egypt. Moshe at some point left his wife and sons in care of his brother-in-law. I would follow a more open-canon approach, and say Chovav is not equal to Yisro, and they are two separate brothers-in-law. And what of Yisro being the priest of Midyan? There could be more than one priest, and/or perhaps he was being trained to succeed his father Reuel when the latter passed on.