Sayyiduna Asad bin Kurz (may Allah be pleased with him) narrates that he heard the Prophet (peace and blessings be upon him) say: "The sins of a sick person fall away just as the leaves of a tree are shed."
Ahmad and al-Tabarani recorded it in al-Mu'jam al-Kabir, and its chain is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجنائز / 3794