Abu Wa'il (may Allah have mercy on him) said: Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) wrote this letter to the people of Persia, inviting them to Islam: "In the name of Allah, the Most Gracious, the Most Merciful. From Khalid bin al-Walid to Rustam, Mihran and the chiefs of Persia. Peace be upon whoever follows the guidance. To proceed: We invite you to Islam. If you refuse, then pay the jizyah by hand while you are humbled, for with me are people who love being killed in the path of Allah just as the Persians love wine. And peace be upon whoever follows the guidance."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3791