I heard the Prophet (ﷺ) saying, "Allah will not deprive you of knowledge after he has given it to you, but it will be taken away through the death of the religious learned men with their knowledge. Then there will remain ignorant people who, when consulted, will give verdicts according to their opinions whereby they will mislead others and go astray."
Sahih al-Bukhari Book 96, Hadith 38
← Previous Hadith I said to Anas, "Did Allah's Messenger (ﷺ) make Medina a sanctuary?" He replied, "Yes, (Medina is a sanctuary from such-and-such place to such-and-such place. It is forbidden to cut its trees, and whoever innovates an heresy in it or commits a sin therein, will incur the curse of Allah, the angels, and all the people." Then Musa bin Anas told me that Anas added, "..... or gives refuge to such an heretic or a sinner..."

Sahih al-Bukhari Book 96, Hadith 37 Next Hadith → I asked Abu Wail, "Did you witness the battle of Siffin between `Ali and Muawiya?" He said, "Yes," and added, "Then I heard Sahl bin Hunaif saying, 'O people! Blame your personal opinions in your religion. No doubt, I remember myself on the day of Abi Jandal; if I had the power to refuse the order of Allah's Messenger (ﷺ), I would have refused it. We have never put our swords on our shoulders to get involved in a situation that might have been horrible for us, but those swords brought us to victory and peace, except this present situation.' " Abu Wail said, "I witnessed the battle of Siffin, and how nasty Siffin was!"

Sahih al-Bukhari Book 96, Hadith 39