Undetermined Cliff (Surah At-Tawbah 9:109-110)

The Difference between Masjid At-Taqwa and Masjid Ad-Dirar

Allah the Exalted says that the Masjid that has been built on the basis of Taqwa of Allah and His pleasure is not the same as a Masjid that was been built based on causing harm, disbelief and causing division among the believers, and as an outpost for those who warred against Allah and His Messenger (Sallallahu Alayhi wa Sallam). The latter built their Masjid on the edge of a steep hole,

into the fire of Hell. And Allah guides not the people who are the wrongdoers, Allah does not bring aright the works of those who commit mischief. Jabir bin `Abdullah (Radhi Allahu Anhu) said, "I saw the Masjid that was built to cause harm with smoke rising up from it, during the time of the Messenger of Allah (Sallallahu Alayhi wa Sallam).'' Allah's statement,

The building which they built will never cease to be a cause of doubt in their hearts  and hypocrisy. Because of this awful action that they committed, they inherited hypocrisy in their hearts, just as those who worshipped the calf were inclined to adoring it. Allah said next,

unless their hearts are cut to pieces,  until they die, according to Ibn `Abbas, Mujahid, Qatadah, Zayd bin Aslam, As-Suddi, Habib bin Abi Thabit, Ad-Dahhak, `Abdur-Rahman bin Zayd bin Aslam and several other scholars of the Salaf.

And Allah is All-Knowing, of the actions of His creation,

All-Wise  in compensating them for their good or evil actions.

Reference: Tafsir ibn Kathir (abridged) English version.