Musnad Ahmad 1153:2190

Rawh narrated to us, he said: Usamah ibn Zayd narrated to us, he said: Ibn Shihab narrated to us, from ‘Urwah, from ‘Aishah, she said: "The Messenger of Allah (ﷺ) would not speak rapidly like this rapid speech of yours. He would speak with speech that was clear and distinct, such that whoever heard it would memorize it."