Umayyah bin Yazid al-Shami narrated, the Messenger of Allah (peace be upon him) said: "Whoever introduces a new practice in Islam, upon him is the curse of Allah, the angels, and all the people; on the Day of Resurrection, neither any voluntary nor any obligatory act will be accepted from him." It was asked: O Messenger of Allah! What is meant by 'hadath'? He (peace be upon him) said: "Whoever kills a soul unjustly or takes revenge without retribution, or invents an innovation without Sunnah." He said: The meaning of «العدل» is: ransom, and the meaning of «الصرف» is: repentance.
Hadith Referenceمسند اسحاق بن راهويه / كتاب الديات / 907