Sahih Bukhari Volume 1, Book 3, Hadith 70

حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، قَالَ حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ أَبِي وَائِلٍ، قَالَ كَانَ عَبْدُ اللَّهِ يُذَكِّرُ النَّاسَ فِي كُلِّ خَمِيسٍ، فَقَالَ لَهُ رَجُلٌ يَا أَبَا عَبْدِ الرَّحْمَنِ لَوَدِدْتُ أَنَّكَ ذَكَّرْتَنَا كُلَّ يَوْمٍ‏.‏ قَالَ أَمَا إِنَّهُ يَمْنَعُنِي مِنْ ذَلِكَ أَنِّي أَكْرَهُ أَنْ أُمِلَّكُمْ، وَإِنِّي أَتَخَوَّلُكُمْ بِالْمَوْعِظَةِ كَمَا كَانَ النَّبِيُّ صلى الله عليه وسلم يَتَخَوَّلُنَا بِهَا، مَخَافَةَ السَّآمَةِ عَلَيْنَا

Narrated By Abu Wail : 'Abdullah used to give a religious talk to the people on every Thursday. Once a man said, "O Aba 'Abdur-Rahman! (By Allah) I wish if you could preach us daily." He replied, "The only thing which prevents me from doing so, is that I hate to bore you, and no doubt I take care of you in preaching by selecting a suitable time just as the Prophet used to do with us, for fear of making us bored."