Nahj al-Balagha (Peak of Eloquence)

Against reliance on heresy O people! If a person knows his brother to be steadfast in faith and of correct ways he should not lend ear to what people may say about him. Sometimes the bowman shoots arrows but the arrow goes astray; similarly talk can be off the point. Its wrong perishes, while Allāh is the Hearer and the Witness. There is nothing between truth and falsehood except four fingers. Amīr al-mu’minīn was asked the meaning of this whereupon he closed his fingers together and put them between his ear and eye and said: It is falsehood when you say, “I have heard so,” while it is truth when you say, “I have seen.”