The Messenger of Allah ﷺ said, "In the latter days a people will emerge who are foolish in mind and young in age, or he said, young in years. They will speak with the finest words people utter, reciting the Quran with their tongues, yet it will not pass beyond their throats. They will pass through Islam as an arrow passes through its prey. Whoever encounters them, let him kill them, for there is a great reward with Allah for whoever kills them."
حدثنا يحيى بن أبي بكير حدثنا أبو بكر بن عياش عن عاصم عن زر
قال رسول الله ﷺ يخرج قوم في آخر الزمان سفهاء الأحلام أحداث أو قال حدثاء الأسنان يقولون من خير قول الناس يقرءون القرآن بألسنتهم لا يعدو تراقيهم يمرقون من الإسلام كما يمرق السهم من الرمية فمن أدركهم فليقتلهم فإن في قتلهم أجرا عظيما عند الله لمن قتلهم
Its isnad is sahih. Ibn Majah related it in 1:39 through Abu Bakr bin Ayyash, and Tirmidhi likewise related it in 3:217, but he abridged it, not mentioning his statement "concerning those whom they reach," etc., and he said, "A hasan sahih hadith." See 1379 and 23120.