The sacred month of Dhul-Qa'dah ذو القعدة is here.
Let's take a moment to learn about this month together.
Dhul Qa'dah/Qi'dah is one of the four sacred months in the Islamic calendar (Dhul Hijjah, Muharram, and Rajab being the other three). These months were also deemed to be sacred in the times of Jahiliyyah.
A reason why these months were chosen was to protect pilgrims traveling to Makkah and back for Hajj and Umrah.
Remember, in those days, it took weeks to travel to other countries so many departed in Dhul Qa'dah.
Dhul Hijjah is the actual month of Hajj. Pilgrims would head home afterwards or in the following month, Muharram. Rajab is in the middle of the year in which many people went to perform Umrah.
Dhul-Qa'dah ذو القعدة was given its name due to bandits sitting (قعود) on the roadways waiting to attack and kill pilgrims heading towards Makkah.
As a result, killings, fighting, wars and expeditions became prohibited during these months.
Also, the severity of performing sins during these months are magnified.
Source: لطائف المعارف لابن رجب