Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
nasai-kubra:770 – Sūwayd b. Naṣr > ʿAbdullāh / Ibn al-Mubārak > Ḥammād b. Salamah > Ayyūb > Abū Qilābah > Anas

"One of the portents of the Hour will be that people will show off in building Masjids." (Using translation from Nasāʾī 689)  

الكبرى للنسائي:٧٧٠ – أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ قَالَ أَخْبَرَنَا عَبْدُ اللهِ يَعْنِي ابْنَ الْمُبَارَكِ عَنْ حَمَّادِ بْنِ سَلَمَةَ عَنْ أَيُّوبَ عَنْ أَبِي قِلَابَةَ عَنْ أَنَسٍ

عَنِ النَّبِيِّ ﷺ قَالَ «إِنَّ مِنْ أَشْرَاطِ السَّاعَةِ أَنْ يَتَبَاهَى النَّاسُ فِي الْمَسَاجِدِ»  

See similar narrations below:

Collected by Nasāʾī, Suyūṭī
nasai:689 – Sūwayd b. Naṣr > ʿAbdullāh b. al-Mubārak > Ḥammād b. Salamah > Ayyūb > Abū Qilābah > Anas

"One of the portents of the Hour will be that people will show off in building Masjids."  

النسائي:٦٨٩ – أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ بْنُ الْمُبَارَكِ عَنْ حَمَّادِ بْنِ سَلَمَةَ عَنْ أَيُّوبَ عَنْ أَبِي قِلاَبَةَ عَنْ أَنَسٍ

أَنَّ النَّبِيَّ ﷺ قَالَ مِنْ أَشْرَاطِ السَّاعَةِ أَنْ يَتَبَاهَى النَّاسُ فِي الْمَسَاجِدِ