What is Masjid Ad-Dirar, and why did the Prophet (peace be upon him) forbid praying in it?

The Mosque of Dissent (Masjid ad-Dirar) was a mosque built by the hypocrites in Madinah with the intention of causing harm, disbelief, and division among the believers, and as a lurking place for Abu 'Amir the Monk, who fought against Allah and His Messenger. They claimed they built it for their weak and sick during winter nights, but Allah disproved their claim and commanded His Prophet never to stand in it, and to demolish and burn it.