Imam Abu Ja'far, that is, Imam Muhammad bin Ali (that is, Imam al-Baqir), states: Sayyidah Fatimah (may Allah be pleased with her) lived for three months after the passing of the Prophet (peace and blessings be upon him). After the passing of the Prophet (peace and blessings be upon him) she was never seen laughing, except that people were in doubt about the edges of her teeth (whether she had smiled).
Al-Tabarani recorded it, and its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 15227