The Torah tells us that Moshe Rabbeinu was amazed at the sight of a thornbush which was burning without getting consumed. As he turned aside to see it from closer, and investigate the phenomenon, Hashem called to him from the midst of the bush, ordering him to remove his shoes as he was standing on holy ground. Hashem did not answer Moshe's unasked question about why the bush was burning, though not getting consumed. The Chasam Sofer explains that Hashem's command "שַׁל‑נְעׄלֶיךָ", was the answer to his question.
The vision of the burning bush, he says, symbolized the Shechinah and the Jewish people who were in exile. The fire, alluding to them, was caught in a thorny situation of Egyptian oppression. Moshe was wondering how these lowly Egyptians were able to hold power over the children of the holy Avos, embittering their lives, and getting away with it. How come the Egyptians were not being "burnt" or punished by Hashem?
"Remove Your Shoes"
In response, Hashem revealed that their salvation was being prevented due to some informers among them. In order for the Jews to be saved, repenting for this sin was required.
This is hinted at in the phrase "שַׁל‑נְעׄלֶיךָ", remove your shoes. According to the Chasam Sofer, this phrase is a reference to the sin of לשׁון הרע, or slander. The letters of נע"ל are an acronym for the words of the possuk נָחָשׁ עָפָר לַחְמוֹ (ישׁעי' סה כה), meaning "the serpent, earth is his food". The Midrash (תנחומא מצוֹרָע ב) explains that, the snake was punished for speaking slander; everything he eats will taste like dust. Thus, the phrase "שַׁל‑נְעׄלֶיךָ" serves as a reminder that the Jews must rid themselves of negative speech and repent for this sin in order to be redeemed from their oppression.
(דרשות חתם סופר קז ד"ה והנה)
We can learn from this the great power of the tongue. The redemption of the entire nation from a terrible exile, was dependent on the them eradicating the sin of Lashon Hora. As long as there were still informers upon them, the salvation could not come. But as soon as they strengthened resolve to guard their tongues, and refrained from gossiping to the Mitzrim that Klal Yisroel would yet get their wealth, the redemption became imminent.