It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him): The strap of the sandal of the Messenger of Allah (peace and blessings be upon him) broke, and he (peace and blessings be upon him) said: "Inna lillahi wa inna ilayhi raji'un (We belong to Allah and to Him we return)." The people asked: Is this a calamity, O Messenger of Allah? He said: "Whatever causes the believer distress is indeed a calamity."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7793