Sahih Bukhari Volume 008, Book 078, Hadith Number 658.
Narated By 'Abdullah bin 'Amr bin Al-As : While the Prophet was delivering a sermon on the Day of Nahr (i.e., 10th Dhul-Hijja-Day of slaughtering the sacrifice), a man got up saying, "I thought, O Allah's Apostle, such-and-such a thing was to be done before such-and-such a thing." Another man got up, saying, "O Allah's Apostle! As regards these three (acts of Hajj), thought so-and-so." The Prophet said, "Do, and there is no harm," concerning all those matters on that day. And so, on that day, whatever question he was asked, he said, "Do it, do it, and there is no harm therein."