(a) Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Let those of sound understanding stand close to me, then those who are like them," saying it three times, and he said: "Beware of making noise in the markets."
(b) In the narration of Muhammad, which he narrates from the Prophet (peace and blessings be upon him): "Let those of understanding stand close to me, then those who are like them, then those who are like them; and do not differ, or your hearts will come to differ. Beware of raising noise in the markets."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5161