Musannaf Ibn Abi Shayba 17:1349

Waki’ narrated to us, from Sufyan, from Abu Ishaq, from Abdullah ibn Khalifah, from Umar ibn al-Khattab, that his sandal strap broke, so he said, "To Allah we belong and to Him we shall return" (istarja’a), and he said, "Everything that causes distress is a calamity."