Al-Hārith al-A‘war said

While passing in the mosque I found the people engrossed in talk, so I went to visit ‘Alī and told him. He asked if that was really so, and when I assured him that it was, he said he had heard Allah's Messenger ﷺ say, “Dissension will certainly come,” and asked him how it could be avoided, to which he replied, “Allah’s Book is the way, for it contains information of what has happened before you, news of what will happen after you, and a decision regarding matters which occur among you (This is explained as a reference to such matters as unbelief and faith, obedience and dis-obedience, what is lawful and what is forbidden, etc.). It is the distinguisher and is not jesting, (Qur’ān, 86:13). If any overweening person abandons it Allah will break him, and if anyone seeks guidance elsewhere Allah will lead him astray. It is Allah’s strong cord, it is the wise reminder, it is the straight path, it is that by which the desires do not swerve nor the tongues become confused, and the learned cannot grasp it completely.* It does not become worn out by repetition and its wonders do not come to an end. It is that of which the jinn did not hesitate to say when they heard it, ‘We have heard a wonderful recital which guides to what is right, and we believe in it,’ (Qur’ān, 72). He who utters it speaks the truth, he who acts according to it is rewarded, he who pronounces judgment according to it is just, and he who invites people to it guides to a straight path.” *The verb used is one ordinarily meaning 'to be satisfied'. Here it is used to indicate that the learned can never learn all there is to be known about the teaching and meaning of the Qur’ān, so that they should be satisfied and feel no need to continue their study of it. Tirmidhī and Dārimī transmit­ted it, Tirmidhī saying this is a tradition whose isnād is unknown, and al-Hārith is adversely criticised.