Êxodo 2:14 Halachá: Chofetz Chaim

Furthermore, is it not well known that exile had already been decreed upon us because of the act of the spies (viz. Tehillim 106:25-27): "And they murmured in their tents [against the land]. They hearkened not to the voice of the L–rd. And He lifted up His hand [in oath] against them… to scatter them in the lands," as Rashi and the Ramban explain there (Bamidbar 14). And the sin of the spies — was it not that of lashon hara! (viz. Arachin 15a). Therefore, it is imperative that we correct this sin before the redemption can take place.

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.