How authentic is this hadith: "Indeed, Allah Almighty, out of His grace and bounty, made saltiness in the eyes of the son of Adam because they are fatty, and were it not for that, they would melt. And indeed, Allah Almighty, out of His grace, bounty, and mercy upon the son of Adam, made bitterness in the ears as a barrier against pests, for if a creature enters the head and seeks to reach the brain, when it tastes the bitterness, it seeks to exit. And indeed, Allah Almighty, out of His grace, bounty, and mercy upon the son of Adam, made warmth in the nostrils by which he inhales air, and were it not for that, the brain would rot. And indeed, Allah Almighty, out of His grace, generosity, and mercy to the son of Adam, made sweetness in the lips by which he tastes everything, and people hear the sweetness of his speech through them"?

This story is narrated in books of athar (traditions) and revolves around Ja'far al-Sadiq and Abu Hanifa.

Abu Hanifa is asked about his name, then Ja'far asks him scientific questions: Did he measure his head? And what is the reason for the salinity in the eyes, the bitterness in the ears, the warmth in the nostrils, and the sweetness in the lips? Ja'far answers him that these are from the bounty of Allah for specific wisdoms.

Then he asks him about a word whose beginning is disbelief and whose end is faith. He answers: "If a servant says 'La Ilaha' (there is no god), he has disbelieved; but if he says 'illa Allah' (except Allah), then it is faith."

Then Ja'far al-Sadiq moves on to prohibiting Abu Hanifa from using qiyas (analogical reasoning) in matters of religion based on opinion, citing that the first to use qiyas was Iblis. He mentions practical examples that show the contradiction of qiyas based on opinion with Sharia, such as accepting two witnesses for murder but four for adultery, and a menstruating woman making up for fasting but not for prayer.

The discourse concludes with a warning to Abu Hanifa against qiyas based on opinion: "Fear Allah, and do not measure religion by your opinion."