Sayyiduna Abu Rafi' (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) was sent as a prophet on a Monday, and Sayyiduna Ali (may Allah be pleased with him) accepted Islam on the Tuesday.
Al-Bazzar recorded it. Its chain contains Muhammad bin Ubaydullah bin Abi Rafi', whom Ibn Hibban declared thiqah (trustworthy) while the majority declared him da'if (weak); the rest of its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 14609