How sound is the story of Imam Al-Shafi'i's refusal to pray over Abu Nuwas due to the presence of a repentance note in his pocket, followed by Al-Shafi'i's weeping and then praying over him?

We have not found any evidence to substantiate the claim that Imam Al-Shafi'i refused to pray over Abu Nuwas. What we did find in Ibn Kathir's "Al-Bidayah wa Al-Nihayah" (The Beginning and the End) is that Al-Shafi'i entered upon Abu Nuwas as he was on his deathbed. Abu Nuwas then recited poetry, acknowledging his sins and hoping for God's forgiveness. Also found at his head was a piece of paper with another poem written on it, expressing his hope for God's forgiveness. This story was narrated by Ibn Asakir and Ibn Kathir, and neither of them mentioned Al-Shafi'i refusing to pray over Abu Nuwas.