Harmful speech and our slavery in Egypt

Hi,

Shemot 2:13-14 says:
"And he [Moshe] went out on the second day and behold, two Hebrews were fighting. He said to the wicked one, "Why will you strike your peer?" The man replied, "Who appointed you as officer and judge over us? Are you declaring that you will kill me, as you killed the Egyptian?" And Moshe was terrified; he said, "The matter is known!""

"Moshe thought in his heart, "What sin did Israel commit, to be the only nation to be enslaved?" When he heard the man's words he said, "They have harmful speech among them! How will they deserve redemption?" Therefore he said, "The matter is known; now I know why they are enslaved."

(Midrash, Shemot Rabbah 1:30)

Have a great day,
Mordechai