Numbers 2 · a question people ask
Why does Judah lead, and not Reuben the firstborn?
Numbers 2 doesn't say. It places Judah on the east and first to set out (2:3, 2:9), and Reuben on the south and second (2:10, 2:16). Other passages speak about the two brothers. Jacob said to Reuben, "you are my firstborn", but "you shall not excel, because you went up to your father’s bed" (Genesis 49:3-4), and of Judah, "The scepter will not depart from Judah" (Genesis 49:10). 1 Chronicles says of Reuben that "his birthright was given to the sons of Joseph", and that "Judah prevailed above his brothers, and from him came the prince" (1 Chronicles 5:1-2). Numbers itself doesn't connect the order of the camp to any of these, so the reason, if there is one, isn't stated here.
The verses
““Those who encamp on the east side toward the sunrise shall be of the standard of the camp of Judah, according to their divisions. The prince of the children of Judah shall be Nahshon the son of Amminadab.”
““All who were counted of the camp of Judah were one hundred eighty-six thousand four hundred, according to their divisions. They shall set out first. “On the south side shall be the standard of the camp of Reuben according to their divisions. The prince of the children of Reuben shall be Elizur the son of Shedeur.”
““All who were counted of the camp of Reuben were one hundred fifty-one thousand four hundred fifty, according to their armies. They shall set out second.”
““Reuben, you are my firstborn, my might, and the beginning of my strength, excelling in dignity, and excelling in power. Boiling over like water, you shall not excel, because you went up to your father’s bed, then defiled it. He went up to my couch.”