(a) Hammam narrates from Sayyiduna Hudhayfah (may Allah be pleased with him) that he led the people in prayer in al-Mada'in on a raised place, so Sayyiduna Abu Mas'ud (may Allah be pleased with him) took hold of his shirt and pulled him. When he finished his prayer, he said: "Do you not know that they used to be forbidden from that?" Or he said: "That has been forbidden." He replied: "Yes! I remembered when you pulled me."
(b) In the narration of Ziyad bin Abdullah al-Bakka'i it is that Sayyiduna Abu Mas'ud (may Allah be pleased with him) said: "Do you not know that the Prophet (peace and blessings be upon him) forbade that the imam stand in a raised place while the people are behind him?"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5232