What is meant by this type of fitnah is the fitnah of the desires which leads to and encourages one to engage in and commit sins or disobedience to Allah.
This type of fitnah is very dangerous especially in our times because of the fact that this type of fitnah is more appealing and closer to those who have weak souls. Thus, the (weak) individual gives in the first time, then gets drawn in to this type of fitnah and establishes a strong foothold in committing sins. Thus, his iman (faith) weakens or even leaves.
Some examples of this type of fitnah are: the desire for wealth, immoralities, amusement, food and drink, clothes, and the desire to imitate the kuffar and sinners. For example, the lust for wealth leads to falling into numerous sins like the bloodshed which emanates between warring countries or between tribes, breaking into people’s homes and businesses or their cars, embezzling people’s money by unlawful means or prohibited means like fraud or selling things which are prohibited.
Lust for immoralities leads to committing unlawful acts like rape, fornication or adultery, homosexuality, masturbation, luring minors or weak minded individuals into committing inappropriate acts. It also leads to watching pornographic channels, videos, on the internet or magazines. It also leads to harassing or following women in shopping malls or with video enhanced networking devices like that are included in mobile phones and computer cameras. In addition to these vices, this type of fitnah leads to lethargy with regards to performing the obligatory actions in addition to leniency with regards to them and even leads to eventually leaving them completely, not performing them at all. An individual may be chaste, have fear of Allah, be religious and then open the door to this type of fitnah and as a result become corrupt and then be destroyed.
Source : Hasten to do good deeds; (there will be) fitnah like a portion of a dark night .. (Must Read) – by: Sheikh Abdul Qaadir Bin Muhammad Al Junaid, Translated By: Abu Afnaan Muhammad Abdullah