On the recommendation to speak plainly and clearly and on repeating things so that the one who did not understood them will understand

Riyad as-Salihin (The Meadows of the Righteous)

by Imam Nawawi

89. Chapter: On the recommendation to speak plainly and clearly and on repeating things so that the one who did not understood them will understand

696. Anas reported that when the Prophet, may Allah bless him and grant him peace, used to say something, he would repeat it three times so that it would be understood. When he came to a people, he would greet them three times." [al-Bukhari]

697. 'A'isha said, "The words of the Messenger of Allah, may Allah bless him and grant him peace, were clear words which could be understood by all who heard them." [Abu Dawud]