Sayyidah Aishah Siddiqah (may Allah be pleased with her) transmits from the Prophet (peace and blessings be upon him): "Other cities were conquered by the sword, and Madinah was conquered by the Qur'an."
Al-Bazzar recorded it; its chain contains Muhammad bin al-Hasan bin Zabalah, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحج / 5776