Summary: A Review of the prophecy of Jacob and the 144 Thousand
The 144 Thousand’s Source-The Twelve Tribes of Israel
The significance of this list of the twelve sons of Jacob is that it provides the basic structure for the list of the twelve tribes found in Revelation 7:4-8 (quickview) . The tribes are listed in Revelation 7:3-8 (quickview) , the last time in Scripture, when later, the 144 Thousand are sealed for protection (Revelation 9:4 (quickview) ) for their future Day of the Lord ministry.
Although there are changes in the order and the specific sons listed, the list in Revelation 7:4-8 (quickview)  has within it definite identifying features showing that this prophesy of Jacob found in the Genesis 49 (quickview)  list has the same underlying structure as the list in Revelation 7:4-8 (quickview) . The sons of Leah are first, then the sons of the two handmaids who are followed by the sons of Rachel, which is the general outline for both lists.
In verse one of Genesis 49 (quickview)  Jacob indicates that what he is going to say will have its effect “in the last days” which points to the time of the end as the period when these prophesies will take place. This prophetic section of the Word of God provides definite insight for those who will be sealed during Daniel’s 70th Week, the last remaining week of the seventy weeks which were determined upon Daniel’s people and their holy city Jerusalem:
“And Jacob called unto his sons, and said, Gather yourselves together, that I may tell you that which shall befall you in the last days. Gather yourselves together, and hear, ye sons of Jacob, and hearken unto Israel your father.” (Genesis 49:1 (quickview) , 2)
Then Jacob addresses his firstborn son Reuben:
“Reuben, thou art my firstborn, my might and the beginning of my strength, the excellency of dignity, and the excellency of power Unstable as water, thou shalt not excel, because thou went up to thy father’s bed; then defiled thou it: he went up to my couch.”
Jacob is referring to the sex sin Reuben committed with Bilhah, Rachel’s handmaid, with whom Jacob fathered two sons, Dan and Naphtali. Reuben’s heinous sin cancelled his birthright, showing his instability, not having the ability to excel due to this defiling conduct which also removed the possibility of God’s blessing.
Simeon and Levi, who are the next two sons born of Leah to Jacob were involved in the cruel sin of mass murder when they slaughtered the defenseless people in the town of Shechem (Genesis 34 (quickview) ). They also do not receive a blessing, instead Jacob pronounces a curse upon them:
”Simeon and Levi are brethren; instruments of cruelty are in their habitations. O my soul come not thou into their secret; unto their assembly, mine honor, be not thou united: for in their anger they slew a man, and in their self will they digged down a wall. Cursed be their anger, for it was fierce, and their wrath, for it was cruel. I will divide them in Jacob, and scatter them in Israel.” (Genesis 49:7-9 (quickview) )