It is disliked for a person to be one who curses

Abu Darda (may Allah be pleased with him) says: I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: Those who curse others will neither intercede for anyone nor bear witness on the Day of Resurrection.

`Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that` it was said to the Messenger of Allah (peace and blessings of Allah be upon him), "O Messenger of Allah! Pray against the polytheists." The Prophet (peace and blessings of Allah be upon him) replied, "I have not been sent to curse people, but rather I have been sent as a mercy (for them)."