What is the ruling on saying: "Oh, black day," when a person receives bad news?

It is not permissible to curse time, due to the prohibition in the Hadith Qudsi: "The son of Adam harms Me; he curses time, while I am time; in My hand is the command, I alternate night and day." What is obligatory when afflicted by a calamity is patience and seeking reward from Allah, and believing that everything is by Allah's decree, in affirmation of His saying, may He be exalted: "No disaster strikes except by permission of Allah. And whoever believes in Allah - He will guide his heart." The meaning of this is that the believer knows that the calamity is from Allah, so he is content and submits.