Maliks Muwatta Book 036, Hadith Number 003.

Section : Giving Testimony.

Yahya related to me from Malik from Abdullah ibn Abi Bakr ibn Muhammad ibn Amr ibn Hazm from his father from Abdullah ibn Amr ibn Uthman from Abu Amra al-Ansari from Zayd ibn Khalid al-Juhani that the Messenger of Allah, may Allah bless him and grant him peace, said, "Shall I not tell you who is the best of witnesses? The one who brings his testimony before he is asked for it, or tells his testimony before he is asked for it."