The Messenger of Allah ﷺ sent his letter to Khosrau, instructing the messenger to deliver it to the governor of Bahrain, who would in turn deliver it to Khosrau. When Khosrau read it, he tore it up.I believe Saeed bin Musayab said, "So the Prophet ﷺ supplicated against them, that they be torn to pieces completely."
أن رسول الله ﷺ بعث بكتابه إلى كسرى، فأمره أن يدفعه إلى عظيم البحرين، يدفعه عظيم البحرين إلى كسرى، فلما قرأه كسرى حرقه. فحسبت أن سعيد بن المسيب قال: فدعا عليهم النبي ﷺ: أن يمزقوا كل ممزق.
Bukhari narrated it in the Book of Jihad and Military Expeditions (2939), from Abdullah bin Yusuf, who said, Layth narrated to us, Aqeel narrated to me, from Ibn Shihab, Ubaydullah bin Abdullah bin Utba informed me that Abdullah bin Abbas informed him, and he related it.As for his statement "so I reckoned," the speaker is Zuhri, and the chain of transmission is connected to what preceded it. Al-Hafiz said, "It occurs in all the transmission routes as mursal, and it is possible that Ibn Musayab heard it from Abdullah bin Hudhafa, the one to whom the story happened..."Refer to Fath al-Bari (127/8).