Sahih Bukhari Volume 008, Book 075, Hadith Number 420.
Narated By Shaqiq : While we were waiting for 'Abdullah (bin Mas'ud). Yazid bin Muawiya came. I said (to him), "Will you sit down?" He said, "No, but I will go into the house (of Ibn Mas'ud) and let your companion (Ibn Mas'ud) come out to you; and if he should not (come out), I will come out and sit (with you)." Then 'Abdullah came out, holding the hand of Yazid, addressed us, saying, "I know that you are assembled here, but the reason that prevents me from coming out to you, is that Allah's Apostle used to preach to us at intervals during the days, lest we should become bored."