ירמיהו, פרק י״א, פסוק י״ד

A harsh directive is handed down from God to His prophet, forbidding him from seeking mercy on behalf of the nation. God explicitly commands Jeremiah not to pray, plead, or raise his voice in supplication for the people. Because God knows that Jeremiah’s prayers are typically desired and accepted, He must directly order the prophet not to act as a defender or serve as a public representative leading prayers for the nation [מלבי״ם].

The core reason for this ban is rooted in the people's own spiritual state. When disaster strikes, the people will inevitably cry out to God to remove their suffering. However, God makes it clear that He will ignore their cries. Their pleas are driven solely by the pain of their current troubles, entirely lacking genuine regret or true repentance for their sins. Since God will not answer the people's cries when they suffer without repenting, it naturally follows that He will not accept the prophet's prayers on their behalf, especially since the people themselves are not offering genuine prayer or changing their ways [מצודת דוד].