It was the practice of the Prophet (peace and blessings be upon him):
"When he (peace and blessings be upon him) stood on the pulpit, his (peace and blessings be upon him) Companions would turn their faces towards him (peace and blessings be upon him)."
Hadith Referenceصحیح الجامع الصغیر / حرف الكاف / 4762
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[هـ] عن ثابت. الصحيحة ٢٠٨٠: ش، هق - عدي بن ثابت.