הלכה אויף דברים 33:5

We may not mention malkhiot, zikhronot and shofarot of punishment — such as [in] zikhronot, "And all flesh shall remember that, etc." (Psalms 78:39); [in] malkhiot, "with outpoured anger shall I rule over you" (Ezekiel 20:33); [and in] shofarot, "Blow the shofar on the mountain, etc." (Hosea 5:8). Nor [may we mention] the remembrance of an individual — even if it was for good — such as "Remember me, O Lord, in the desire of Your people" (Psalms 106:4); and "Remember me, my God, for the good" (Nehemiah 13:31). And recollections (pikdonot) — such as "I have surely recalled you" (Exodus 3:16) — are not the same as remembrances. But one may mention the punishment of idolatrous nations, such as "The Lord reigned, nations tremble" (Psalms 99:1); "Remember the day of Jerusalem to the Children of Edom" (Psalms 137:7); [and] "the Lord, God, will blow with the shofar, and go in the storms of the south" (Zechariah 9:14). All of these verses: "Hear Israel, the Lord, our God, the Lord is one" (Deuteronomy 6:4); "You have been shown to know" (Deuteronomy 4:35); "And you shall know today and place upon your hearts, etc." (Deuteronomy 4:39) — their content is kingship. Even though there is no mention of kingship [in them], it is surely like, "The Lord will reign forever and ever" (Exodus 15:18); [and] "And then He became King in Jeshurun, etc." (Deuteronomy 33:5).

And we find it explicitly stated that it was this sin which caused the Jews to be worked [by the Egyptians] with back-breaking labor (viz. Shemoth 2:14 and Rashi there). And (Devarim Rabbah 6:14): "The Holy One Blessed be He said: 'In this world, because there was lashon hara among you, I removed My Shechinah from you, but in the next world, etc.'" And (Devarim 33:5): "And He became a King in Yeshurun when the heads of the people were gathered together as one, the tribes of Israel," which Rashi interprets (as per Sifrei): "When is He a King in Israel? Specifically, when the tribes of Israel are united and not divided into factions" — which (factions) are well known to be the result of lashon hara.