The Messenger of Allah ﷺ said, "In the last days, Some men will emerge who deceive the world through religion. They will clothe themselves before people in the skins of sheep for their softness. Their tongues will be sweeter than sugar, but their hearts will be the hearts of wolves. Allah says, 'Is it Me they seek to deceive, or is it against Me that they dare? By Myself I swear, I shall send upon those among them a trial that will leave even the forbearing among them bewildered.'"
حدثنا سويد أخبرنا ابن المبارك أخبرنا يحيى بن عبيد الله قال سمعت أبي يقول سمعت
قال رسول الله ﷺ يخرج في آخر الزمان رجال يختلون الدنيا بالدين يلبسون للناس جلود الضأن من اللين ألسنتهم أحلى من السكر وقلوبهم قلوب الذئاب يقول الله عز وجل أبي يغترون أم علي يجترئون فبي حلفت لأبعثن على أولئك منهم فتنة تدع الحليم منهم حيرانا
[Its isnad is extremely daif]. It is found in Kitab al-Zuhd by Ibn Mubarak, no. 50. See the preceding hadith for its defect. There is also a version on this topic from Ibn Umar [to come: 2405].