Have faith in Allah and His Messenger1 and strive in the Way of Allah with your possessions and your lives. That is better for you if you only knew.2
Footnotes
[1]
When the believers are asked to believe, it automatically gives the meaning that they should become sincere Muslims: they should not rest content with oral profession of the faith but should be ready and willing to make every sacrifice in the cause of their faith.
[2]
That is, this bargain is far superior for them to every worldly bargain.