ISTIKHFAAF in the context of the Shariah means to consider any act of the Deen to be insignificant, ‘small’ or light. Istihza’ means to view with mirth or to make a joke of any Deeni issue, or to mock at it. Both these attitudes are kufr.
Rasulullah (sallallahu alayhi wasallam) warned a gainst cupping (hijaamat) on Saturdays and Thursdays. There is the danger of contracting the disease of leprosy if cupping is done on these days. A Muhaddith who had classified this Hadith as Dhaeef (Weak) had deliberately had himself cupped on a Saturday. In consequence he contracted leprosy.
After some time, he saw Rasulullah (sallallahu alayhi wasallam) in a dream, and he (the Muhaddith) complained about his disease. Rasulullah (sallallahu alayhi wasallam) said: “Why did you resort to cupping on a Saturday?” The Muhaddith said: “O Rasulullah! (Sallallahu alayhi wasallam) The raawi (narrator) of this Hadith is Dhaeef.”
Rasulullah (sallallahu alayhi wasallam) said: “But it was attributed to me.” The Muhaddith said: “O Rasulullah? (sallallahu alayhi wasallam) I have erred. I repent.” Then Rasulullah (sallallahu alayhi wasallam) made dua for his shifa’ (cure). In the morning when the Muhaddith opened his eyes, there was not a sign of the leprosy on him.
Beware of nafsaani dismissal of Ahaadith. Dhaeef Ahaadith are not fabrications. Your aversion for Hadith can be calamitous for you.