|Art by Nick Gustafson|
Moses cried out to the Lord concerning the frogs that He had brought upon Pharaoh....And the Lord did according to Moses' word, and the frogs died .... [Va'eira 8:8-9]
Why is it, asked the Chofetz Chaim, that at the Plague of Frogs, Hashem accepted Moshe's prayer as soon as he uttered it and immediately stopped the devastating plague, yet when the Jews were in the wilderness and were attacked by fiery serpents, Moshe's prayers did not have an immediate effect?
For, in that case, Hashem told Moshe: ''Make yourself [the image of] a venomous snake, and place it on a pole.'' [Bamidbar 21:8] Only by gazing at the copper ''snake'' did those who were bitten survive.
Why was it necessary for Moshe to perform an action here in order to save the Jewish people in the wilderness, yet in Egypt, no additional action was required?
This is meant to teach us, answered the Chofetz Chaim, the severity of the sin of speaking lashon hara.
As a rule, prayer is effective for removing all misfortunes and calamities. Therefore, when Moshe beseeched Hashem to remove the frogs from Egypt, Hashem accepted his prayer and instantly stopped the plague. However, the fiery serpents were sent to attack the Jewish people as a punishment for speaking lashon hara.
Since they had committed a sin which the Heavenly Court judges with exactitude, Moshe's prayers were not immediately effective. Instead, Hashem instructed him to make an image of a venomous snake for the people to gaze at. This way, each Jew would think of his Father in Heaven and personally repent for his sin. Each Jew would then be forgiven and granted life.
Source: Rabbi Yisroel Bronstein