Translation:

23. Among the Believers are men who have been true to their Covenant with Allah: of them some have completed their vow to (the extreme) and some (still) wait: but they have never changed (their determination) in the least:

Notes (Tafseer)

3697. In the fight for truth were (and are) many who sacrificed their all-resources, knowledge, influence, life itself-in the Cause, and never wavered. If they won the crown of martyrdom, they were blessed. Such a one was Sad ibn Mu'az, the chief of the Aus tribe, the intrepid standard-bearer of Islam, who died of a wound he had received in the Battle of the Trench. Other heroes fought valiantly and lived, always ready to lay down their lives. Both classes were staunch: they never changed or wavered.