إِنَّ مِنْ أَشْرَاطِ السَّاعَةِ أَنْ يَتَبَاهَى النَّاسُ فِي الْمَسَاجِدِ
Among the signs of the Hour is that people boast to one another concerning mosques.
Source: أبو داود
أَشْرَاطِ السَّاعَةِ means “signs of the Hour,” and يَتَبَاهَى means “boast or vie with one another.” The warning concerns using mosques as a setting for rivalry and display.
مِنْ أَشْرَاطِ means “among the signs.” النَّاسُ indicates the people engaging in the action expressed by يَتَبَاهَى, and فِي الْمَسَاجِدِ connects that action with mosques.
The narration does not, by its wording alone, condemn cleanliness, sound construction, or all suitable decoration. Its stated concern is boasting about mosques.