صحيح البخاري Sahih Bukhari كتاب العلم The Book of Knowledge
بَابُ مَا يُذْكَرُ فِي الْمُنَاوَلَةِ وَكِتَابِ أَهْلِ الْعِلْمِ بِالْعِلْمِ إِلَى الْبُلْدَانِ:

(7) Chapter. What is said regarding the hand to hand exchange (of books of knowledge), and the writing of knowledge by religious scholars to different countries.

2 hadith
Hadith 64
حَدَّثَنَا إِسْمَاعِيلُ بْنُ عَبْدِ اللَّهِ ، قَالَ : حَدَّثَنِي إِبْرَاهِيمُ بْنُ سَعْدٍ ، عَنْ صَالِحٍ ، عَنِ ابْنِ شِهَابٍ ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ بْنِ مَسْعُودٍ ، أَنَّ عَبْدَ اللَّهِ بْنَ عَبَّاسٍ أَخْبَرَهُ ، " أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ بَعَثَ بِكِتَابِهِ رَجُلًا وَأَمَرَهُ أَنْ يَدْفَعَهُ إِلَى عَظِيمِ الْبَحْرَيْنِ ، فَدَفَعَهُ عَظِيمُ الْبَحْرَيْنِ إِلَى كِسْرَى ، فَلَمَّا قَرَأَهُ مَزَّقَهُ ، فَحَسِبْتُ أَنَّ ابْنَ الْمُسَيَّبِ ، قَالَ : فَدَعَا عَلَيْهِمْ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنْ يُمَزَّقُوا كُلَّ مُمَزَّقٍ " .
Narrated `Abdullah bin `Abbas: Once Allah's Apostle gave a letter to a person and ordered him to go and deliver it to the Governor of Bahrain. (He did so) and the Governor of Bahrain sent it to Chousroes, who read that letter and then tore it to pieces. (The sub-narrator (Ibn Shihab) thinks that Ibn Al-Musaiyab said that Allah's Apostle invoked Allah against them (saying), "May Allah tear them into pieces, and disperse them all totally.)"
Hadith Reference Sahih Bukhari / The Book of Knowledge / Hadith: 64
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة
Hadith 65
حَدَّثَنَا مُحَمَّدُ بْنُ مُقَاتِلٍ أَبُو الْحَسَنِ الْمَرْوَزِيُّ ، أَخْبَرَنَا عَبْدُ اللَّهِ ، قَالَ : أَخْبَرَنَا شُعْبَةُ ، عَنْ قَتَادَةَ ، عَنْ أَنَسِ بْنِ مَالِكٍ ، قَالَ : " كَتَبَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كِتَابًا أَوْ أَرَادَ أَنْ يَكْتُبَ ، فَقِيلَ لَهُ : إِنَّهُمْ لَا يَقْرَءُونَ كِتَابًا إِلَّا مَخْتُومًا ، فَاتَّخَذَ خَاتَمًا مِنْ فِضَّةٍ نَقْشُهُ مُحَمَّدٌ رَسُولُ اللَّهِ كَأَنِّي أَنْظُرُ إِلَى بَيَاضِهِ فِي يَدِهِ ، فَقُلْتُ لِقَتَادَةَ : مَنْ قَالَ نَقْشُهُ مُحَمَّدٌ رَسُولُ اللَّهِ ؟ قَالَ : أَنَسٌ " .
Narrated Anas bin Malik: Once the Prophet wrote a letter or had an idea of writing a letter. The Prophet was told that they (rulers) would not read letters unless they were sealed. So the Prophet got a silver ring made with "Muhammad Allah's Apostle" engraved on it. As if I were just observing its white glitter in the hand of the Prophet.
Hadith Reference Sahih Bukhari / The Book of Knowledge / Hadith: 65
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة