Musnad Ahmad 30:1101

The Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah, the Mighty and Majestic, says: 'My servant has denied Me, and that is not for him [to do]. And he has insulted Me, and that is not for him [to do]. His denying Me is his saying: "He will not bring us back as He began us." As for his insulting Me, it is his saying: "Allah has taken a son," while I am the Eternal Refuge (As-Samad), who has not begotten and was not begotten, and there is none co-equal to Me.'"