Wathilah bin Al-Asqa' narrated that the Messenger of Allah (s.a.w) said:
"Do not rejoice over the mishaps of your brother so that Allah has mercy on him and subjects you to trials." (RU)
English reference (RU): Vol. 4, Book 11, Hadith 2506 (RU)
Arabic reference (RU): Book 37, Hadith 2694 (RU)