Sayyiduna Anas (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) used to make these supplications in the morning and in the evening:
'Allahumma inni as'aluka min faj'atil-khayr, wa a'udhu bika min faj'atish-sharr'
"O Allah, I ask You for good that comes suddenly, and I seek refuge with You from evil that comes suddenly."
For no servant knows what will suddenly befall him in the morning or in the evening.
Abu Ya'la recorded it, and its chain contains Yusuf bin Atiyyah, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 17001