Harith ibn Abi Shamir Al-Gassani (Arabic: اَلْحَارِث ٱبْن أَبِي شَمِر الغَسَّانِي, romanized: al-Ḥārith-bn-Abī-Shamir al-Ghassānī) was the Ghassanid Arab Christian governor of Sham (Levant or Greater Syria) which was in the domain of the Byzantine Empire. He was a contemporary of Muhammad and King of Damascus now in modern-day Syria. He received a letter from Muhammad in which he was invited to Islam. Harith was a member of the Ghassanid dynasty, which ruled parts of Sham.

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After the Hudaybiyah Treaty, Muhammad sent a letter to Harith Gassani which read as follows:

بسم الله الرحمن الرحيم، من محمد رسول الله إلى الحارث بن أبي شمر، سلام على من اتبع الهدى، وآمن به وصدق، وإني أدعوك إلى أن تؤمن بالله وحده لا شريك له، يبقى لك ملكك^{[This quote needs a citation]}

From Muhammad the Messenger of God to Al-Harith bin Abi Shamir:

Peace be upon him who follows true guidance and believes in it and regards it as true. I invite you to believe in One God with no associates, and your kingdom shall remain yours.^[1]

• Non-Muslims Interactants with Muslims During Muhammad's Era
• Muqawqis