Musnad Ahmad 32:547

Azhar ibn al-Qasim narrated to us, Hisham narrated to us, from Qatadah, from Anas, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Some people will certainly be afflicted by the scorching of the Fire as a punishment for sins they committed. Then, Allah will cause them to enter Paradise by the grace of His mercy. It will be said to them: 'The Jahannamiyyun (the people of Hell).'"