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." (DE)
English reference (DE): Vol. 4, Book 11, Hadith 2506 (DE)
Arabic reference (DE): Book 37, Hadith 2694 (DE)