Kabbalah sur Les Nombres 2:3

And because of that obligation his sons died, since they sickened their ways and did not combine Day with Night, and so they did not win favor, just as one who sees white [compassion] in the red [judgment] on one's friend, in that one can save one's friend's obligation but splits from the friend at the outset. In that same way a righteous person, who is called Day, cannot split from the Congregation of Israel which is called Night. And the hint is given by the Holy One of Blessing, to bring East and West close to one another, and said to the righteous: "Camped on the front, east side, the flag of the camp of Yehuda" - to bring East and West close, bringing to him the Flow of Blessings from Above.