Imam Ibnul Qaiyum said:
Temptations which are presented to the heart are a cause for its sickness, it is the temptations of desires and temptations of doubts…..
Imam Albani commented saying:
They (the temptations of desires and doubts) are the origin for every evil.
Ighaathatul Lahfaan 1/42
Majid Jawed Al Afghaanee