17 But perchance some one may object, and say, “It is this, then, that saddens me in the present mortality, that I, who had been prepared for confession, and had devoted myself to the endurance of suffering with my whole heart and with abundant courage, am deprived of martyrdom, in that I am anticipated by death.” In the first place, martyrdom is not in your power, but in the condescension of God; neither can you say that you have lost what you do not know whether you would deserve to receive.
Then, besides, God the searcher of the reins and heart, and the investigator and knower of secret things, sees you, and praises and approves you; and He who sees that your virtue was ready in you, will give you a reward for your virtue. Had Cain, when he offered his gift to God, already slain his brother? And yet God, foreseeing the fratricide conceived in his mind, anticipated its condemnation. As in that case the evil thought and mischievous intention were foreseen by a foreseeing God, so also in God's servants, among whom confession is purposed and martyrdom conceived in the mind, the intention dedicated to good is crowned by God the judge.
It is one thing for the spirit to be wanting for martyrdom, and another for martyrdom to have been wanting for the spirit. Such as the Lord finds you when He calls you, such also He judges you; since He Himself bears witness, and says, “And all the churches shall know that I am the searcher of the reins and heart.” For God does not ask for our blood, but for our faith. For neither Abraham, nor Isaac, nor Jacob were slain; and yet, being honoured by the deserts of faith and righteousness, they deserved to be first among the patriarchs, to whose feast is collected every one that is found faithful, and righteous, and praiseworthy.
Source: The Treatises of Cyprian (New Advent)