Genesis 12:2
2 And I
will make of you a great nation, and I will bless you, and make your name great;
and you shall be a blessing.
3 And I will bless them that bless you, and curse him that curses you: and
in you shall all families of the earth be blessed.
Abraham
had a son named Isaac and Isaac’s son was named Jacob. Eventually God
changed Jacob’s name to Israel. Jacob (or Israel) had 12 sons who became
the fathers of the 12 tribes of Israel. One of those sons was named Judah.
All of those who are descendents of Judah are known as Jews, just as the
descendents of Levi are known as Levites. The descendents of Judah have
specific blessings, recorded in Genesis 49:8-12.
8
"Judah, your brothers will praise you; your hand will be on the neck of
your enemies; your father's sons will bow down to you.
9 You are a lion's cub, O Judah; you return from the prey, my son. Like a
lion he crouches and lies down, like a lioness--who dares to rouse him?
10 The scepter will not depart from Judah, nor the ruler's staff from
between his feet, until he comes to whom it belongs and the obedience of
the nations is his.
11 He will tether his donkey to a vine, his colt to the choicest branch;
he will wash his garments in wine, his robes in the blood of grapes.
12 His eyes will be darker than wine, his teeth whiter than milk.
From this prophecy we see that
the kings of Israel were to come from the descendents of Judah, and the Messiah
would also come from this line.