Abu Hazim (may Allah have mercy on him) relates that he heard Sayyiduna Sahl bin Sa'd al-Sa'idi (may Allah be pleased with him) when he was being asked about the pulpit: what wood was it made of? He said: The Messenger of Allah (peace and blessings be upon him) sent a message to a woman, whom he named, and said: "Tell your slave, the carpenter, to make me some pieces of wood on which I can sit and address the people." So he made these three steps for him from the tamarisk wood of al-Ghabah. The Prophet (peace and blessings be upon him) gave the order, and they were placed in this spot. Sahl (may Allah be pleased with him) said: I saw the Prophet (peace and blessings be upon him) on the first day he sat on it: he said the takbir, and the people said the takbir behind him; then he bowed while on the pulpit, then raised his head, then stepped down backwards and prostrated at the foot of the pulpit; then he went back up, until he completed his prayer, doing in the rest of it just as he had done in the first rak'ah. When the Prophet (peace and blessings be upon him) finished, he turned to the people and said: "O people, I did this only so that you would follow me and learn my prayer."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5860