‘Abdallah b. ‘Umar told that he heard God’s Messenger say, “If anyone’s intercession intervenes as an obstacle to one of the punishments prescribed by God he has opposed God; if anyone disputes knowingly about something which is false he remains in the displeasure of God most high till he desists; and if anyone makes an untruthful accusation against a Muslim he will be made by God to dwell in the corrupt fluid flowing from the inhabitants of hell* till he retracts his statement.”
Ahmad and Abu Dawud transmitted it.
* Radghat al-khabal.
In a version by Baihaqi in Shu’ab al-iman it says, “He who assists in a dispute, not knowing whether it is true or false, will remain in God’s displeasure till he desists.”