"No soul can die except by Allah's leave, the term being fixed as by writing."
"Nor is a man long-lived granted length of days, nor is a part cut
off from his life, but is in a Decree (ordained). All this is easy to Allah."
For these two ayaat, the author says that they will make the cowards become
courageous and lay down their lives when necessary and fight for Allah's cause.
Because courage does not decrease your life and cowardice does not increase it.
No matter how courageous you are, that is not going to decrease your life.
And no matter how much fear you have, that is not going to increase your life.
If a mo'min reaches the level of yaqeen where he realizes that his death is at an appointed time and
nothing can stop it, he will be very courageous; he will fear nothing.
He will see all the enemies of Allah as just mere creatures that are controlled by Allah.
So why fear them?
150. So from whencesoever Thou startest forth, turn Thy face in the direction of the sacred Mosque;
and wheresoever ye are, Turn your face thither:
that there be no ground of dispute against you among the people, except those of them that are bent on wickedness;
so fear them not, but fear Me; and that I may complete My favours on you, and ye May (consent to) be guided;
151. A similar (favour have ye already received) in that We have sent among you an Messenger of your own, rehearsing to you Our Signs, and sanctifying you, and instructing you in Scripture and Wisdom, and in new knowledge.
152. Then do ye remember Me; I will remember you. Be grateful to Me, and reject not Faith.
153. O ye who believe! seek help with patient perseverance and prayer; for Allah is with those who patiently persevere.
154. And say not of those who are slain in the way of Allah. "They are dead." Nay, they are living, though ye perceive (it) not.
155. Be sure we shall test you with something of fear and hunger, some loss in goods or lives or the fruits (of your toil), but give glad tidings to those who patiently persevere,
156. Who say, when afflicted with calamity: "To Allah We belong, and to Him is our return":-
157. They are those on whom (Descend) blessings from Allah, and Mercy, and they are the ones that receive guidance.
Quran Ch, Al Baqrah.
Khalid bin al Waleed would be so courageous that he would throw himself into the army ranks and had said about himself,
"I would throw myself in the ranks of the enemies until I would be certain that I would not come out alive.
And here I am dying on my bed.
So may the eyes of the cowards never see sleep!"
He made du'a against the cowards implying how can you be a coward when courage did not kill him.