What is the ruling on citing weak hadiths as evidence?

It is not permissible to use weak hadiths as evidence or to present them as proof unless their weakness is clarified. This is based on the Prophet's (peace and blessings be upon him) saying: "Whoever narrates a hadith from me, believing it to be a lie, is one of the two liars." However, some scholars have permitted narrating weak hadiths under three conditions: that the weakness not be severe, that it have a sound basis, and that one not believe the Prophet (peace and blessings be upon him) actually said it, but rather narrate it using a probabilistic (mumarraḍah) صيغة (form/wording). It is obligatory for a scholar who knows a widespread hadith to be weak to clarify its weakness. And whoever propagates weak hadiths or baseless stories is sinful, especially if they are fabricated, because he misleads people and frightens or encourages them with something that is not sound.