Believers are people who make earning the approval of Allah the ultimate purpose of their lives and strive hard for this cause. In the Qur’an, Allah calls them the ones who strive with their properties and their lives in the cause of Allah. 1 Because they have devoted their lives to Allah and are willing to offer everything they have, material and otherwise, for the pleasure of Allah and Paradise, believers have a very important attribute that enables them to commit themselves and to say under the most trying circumstances: "Sufficient for us is Allah."2 It is their eagerness to earn the approval of Allah.
The zeal granted by faith is a power that increases one’s physical and mental capacity, enabling him to lead every moment of his life in the best and most productive way. This enthusiasm consequential to love of Allah provides a person with spiritual power, great strength and resistance, a steel-like will and courage. Through spiritual power believers overcome every difficulty and continue to strive hard for Allah whatever the conditions and circumstances may be.
This book discusses the zeal of believers that continues to increase until the end of their lives. Its purpose is to encourage all Muslims to be more zealous by showing how great a blessing zeal is as an attribute which strengthens believers. The reader will understand the important secret that makes one successful even under the most difficult conditions. Furthermore, he will learn of the bounties that have been promised to those who never lose their zeal and who meet difficulties by putting their trust in Allah. This book encourages people to comply with His directive:
"Hasten to forgiveness from your Lord and a garden [i.e., Paradise] as wide as the heavens and earth."3
An additional aim is to motivate those who merely follow a middle course when living the principles of Islam and feel satisfied with this rather than striving to be among the forerunners.