Does following weak hadiths constitute polytheism, and if the hadiths are not authentic, do we fall into polytheism, taking into account Allah Almighty’s saying: “Do they not then reflect upon the Qur’an? And if it were from [any] other than Allah, they would have found within it much inconsistency”?

Working with weak (da'if) hadith (definition) is not considered shirk (definition) (polytheism). Weak hadith may not necessarily be fabricated; their weakness might stem from a narrator's poor memory or error. It is permissible to act upon a weak hadith under three conditions: that its weakness is not severe, that the hadith falls under a general principle such as the فضائل الأعمال (virtues of deeds), and that one does not believe in its definitive authenticity when acting upon it. Discrepancies between hadith may arise from a narrator's error or from abrogation (naskh), but there are no discrepancies in authentic and firmly established hadith. Some scholars have permitted working with weak hadith regarding the virtues of deeds, but not in matters of rulings (ahkam). As Imam Ahmad said, "When we narrate concerning the lawful and the unlawful, we are strict; but when we narrate concerning virtues, we are lenient."