Against reliance on heresy
Nahj al-Balāgha|Volume 1|Book 1|Chapter 141
فسئل (عليه السلام) عن معنى قوله هذا، فجمع أصابعه ووضعها بين أذنه وعينه ثمّ قال: الْبَاطِلُ أَنْ تَقُولَ سَمِعْتُ، وَالْحَقُّ أَنْ تَقُولَ رَأَيْتُ!
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.”