(a) Nafi' narrates from Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) used to deliver two sermons. When he ascended the pulpit, he (peace and blessings be upon him) would sit until the mu'adhdhin had finished the call to prayer, then he (peace and blessings be upon him) would stand and deliver the sermon. Then he would sit and not speak to anyone, then he would stand and deliver the sermon.
(b) Anas bin Malik (may Allah be pleased with him) relates the story of the pulpit, that they made for him (peace and blessings be upon him) a pulpit with two steps, and he (peace and blessings be upon him) would sit on the third. When the Prophet (peace and blessings be upon him) sat on it, the trunk began to weep.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5747