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.
ahmad-zuhd:1870ʿAbdullāh > ʿAlī b. Muslim > Sayyār > Jaʿfar > Mālik > al-Qalb Idhā Lam Yakun Fīh Ḥuzn Kharib Kamā

[Machine] I heard Malik saying, "If the heart is not sad, it will be destroyed just like a house that is not inhabited will be destroyed."  

الزهد لأحمد:١٨٧٠حَدَّثَنَا عَبْدُ اللَّهِ حَدَّثَنِي عَلِيُّ بْنُ مُسْلِمٍ حَدَّثَنَا سَيَّارٌ حَدَّثَنَا جَعْفَرٌ

سَمِعْتُ مَالِكًا يَقُولُ «الْقَلْبُ إِذَا لَمْ يَكُنْ فِيهِ حُزْنٌ خَرِبَ كَمَا أَنَّ الْبَيْتَ إِذَا لَمْ يُسْكَنْ خَرِبَ»