Translation:

29. But if ye seek Allah and His Apostle and the Home of the Hereafter verily Allah has prepared for the well-doers amongst you a great reward.

Notes (Tafseer)

3707. They were all well-doers. But being in their exalted position, they had extra responsibility, and they had to be specially careful to discharge it. In the same way their reward would be "great", for higher services bring higher spiritual satisfaction, though they were asked to deny themselves some of the ordinary indulgences of this life.