الأخلاق الذميمة
Wāthilah ibn al-Asqa‘ (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Do not rejoice at the misfortune of your brother, lest Allah should have mercy on him and subject you to affliction."
عن واثلة بن الأسْقَع -رضي الله عنه- قال: قال رسول الله -صلى الله عليه وسلم-: «لا تُظهر الشَّمَاتَة لأخيك فَيَرْحَمَه الله ويَبْتَلِيك».
شرح الحديث :
If a Muslim is afflicted with a calamity in his religion, his wealth, or his worldly affairs, and there happens to be animosity between you and him, then you must not rejoice at his calamity, nor speak of it among the people with joy at what happened to him and as a way of undermining him. It is the proper character of a Muslim to feel the pain of his Muslim brother and to rejoice at his happiness, not the opposite. Perhaps Allah might relieve him of what He afflicted him with and afflict you with it as a just recompense. Though this Hadīth is classified as weak, its meaning is correct, as indicated by other general texts from the Qur'an and authentic Sunnah. Allah, the Almighty, says: {O you who have believed, let not a people ridicule [another] people; perhaps they may be better than them.} [Sūrat al-Hujurāt: 11]