Tufail bin `Amr Ad-Dausi and his companions came to the Prophet (ﷺ) and said, "O Allah's Messenger (ﷺ)! The people of the tribe of Daus disobeyed and refused to follow you; so invoke Allah against them." The people said, "The tribe of Daus is ruined." The Prophet (ﷺ) said, "O Allah! Give guidance to the people of Daus, and let them embrace Islam."
Sahih al-Bukhari Book 56, Hadith 150
← Previous Hadith Allah's Messenger (ﷺ) wrote a letter to Caesar saying, "If you reject Islam, you will be responsible for the sins of the tillers (i.e. your people).

Sahih al-Bukhari Book 56, Hadith 149 Next Hadith → When the Prophet (ﷺ) intended to write a letter to the ruler of the Byzantines, he was told that those people did not read any letter unless it was stamped with a seal. So, the Prophet (ﷺ) got a silver ring-- as if I were just looking at its white glitter on his hand ---- and stamped on it the expression "Muhammad, Apostle of Allah".

Sahih al-Bukhari Book 56, Hadith 151