Zayd bin Khalid reported,

The Messenger of Allah ﷺ said, "Shall I not tell you of the best of witnesses? It is the one who comes forward with his testimony before being asked for it, or who gives his testimony before it is requested."

Azami 6742

Sahih

عن زيد بن خالد الجهني

أن رسول الله ﷺ قال: ألا أخبركم بخير الشهداء؟ الذي يأتي بشهادته قبل أن يسألها، أو يخبر بشهادته قبل أن يسألها.

الأعظمي 6742صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Judgeship
Chapter
Testimonies
Section
Best witness is one who gives his testimony before being asked for it, out of fear that rights may be lost
Numbering
Jami al-Kamil 6742 (2nd edition)
Azami 6742