The Quran

Preface

وَالَّذينَ آمَنوا بِاللَّهِ وَرُسُلِهِ أُولٰئِكَ هُمُ الصِّدّيقونَ ۖ وَالشُّهَداءُ عِندَ رَبِّهِم لَهُم أَجرُهُم وَنورُهُم ۖ وَالَّذينَ كَفَروا وَكَذَّبوا بِآياتِنا أُولٰئِكَ أَصحابُ الجَحيمِ

Yusuf Ali

And those who believe in God and His messengersthey are the Sincere¹ (lovers of Truth), and the witnesses (who testify),² in the eyes of their Lord: They shall have their Reward and their Light.³ But those who reject God and deny Our Signs,- they are the Companions of Hell-Fire.

Cf. 4:69, and n. 586. The four categories there mentioned as constituting the beautiful Fellowship of Faith are: the Prophets who teach, the Sincere Lovers of Truth, the Witnesses who testify, and the Righteous who do good. Of these, the prophets or messengers have already been mentioned in this verse. The Righteous who do good are mentioned as the men and women given over to deeds of charity in verse 18.
The Witnesses are not only Martyrs, but all those who carry the Banner of Truth against all odds and in all positions of danger, whether by pen or speech, or deed or counsel.
Note that these two are specially high degrees in the spiritual kingdom, just short of Prophethood. For they have not only their reward in the spiritual Kingdom of God, like those who practise charity (verse 18 above), but they themselves become sources of light and leading.