Question: When I commit a sin, I delay repentance on the grounds that I may commit it again later. Is there anything wrong with delaying repentance? In order to make repentance, does it suffice to say only "I repent"?
ANSWER
After every sin, it is fard (obligatory) to make repentance immediately. The sin doubles in amount if repentance is delayed for one hour. Saying only "I repent" is not counted as repentance because three conditions must be fulfilled in order for one's repentance to be valid:

1. One must cease committing that sin right away,

2. One must, out of fear of Allahu ta'ala, feel ashamed of and be full of remorse for the sin one has committed,

3. One must make a heartfelt promise not to do that sin again in the future. Allahu ta'ala has promised that He will accept repentance if it meets the conditions set for it.

Question: Is it another sin not to repent of a sin or to delay repentance?
ANSWER
Yes, it is another sin. Hadrat Muhammad Ma'sum stated:
Not repenting of a sin is worse than committing that sin. (Vol. 2, Letter 110)

It is fard to make repentance after every sin. When repentance is delayed for one hour, the sin will double. (Documents of the Right Word)

Question: It is said, "If repentance is delayed for one hour, the sin will double." It is also said, "When one commits a sin, angels do not record it until three hours pass. If one does not make repentance during this period of time, then it will be recorded." What is the fine distinction between these two statements?
ANSWER
When an hour passes without repentance after a sin, that sin grows. However, if one repents of it within three hours, no sin will be recorded. If one does not repent of it within three hours, the sin will be doubled and will be recorded as twofold.