Musnad Abu Ya'la al-Mawsili 149:113

Ibrahim ibn al-Hajjaj narrated to us, Hammad narrated to us, from Abd al-Rahman ibn al-Qasim, from al-Qasim ibn Muhammad, from Aisha, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The people who will receive the severest punishment on the Day of Resurrection are those who imitate the creation of Allah."