Dul al-Qudah is also known as Zulqida is the 11th month in the Islamic calendar. It is one of the four sacred months in Islam during which War is prohibited.

The Islamic calendar is known as a Luna Calendar and months start when the first crescent of the new moon is being sighted. The Islamic lunar calendar year is 11 or 12 days shorter than the tropical year, Dhu Al-Qidah moves throughout the season.

Dhu al-Qidah Important Dates

1st Dhu al-Qidah: Treaty of Hudaybiyyah.
8th Dhu al-Qidah: Hajj was made mandatory for Muslims (at least once in a lifetime).
11th Dhu al-Qidah: Birth of Ali al-Ridha.
18th Dhu al-Qidah: The event of Ghadir Khumm (10 A.H.)
25th Dhu al-Qidah: Birth of Ibrahim (AS) and Isa (AS) also known as Jesus.
25th Dhu al-Qidah: It was the day when the earth was laid beneath the Kaaba.

Other mentions include;

5 AH: Muslims fought the Battle of the Trench.
6 AH: Pledge of the Tree.
7 AH: The First Umrah was performed by Prophet Muhammad PBUH with his companions.

All information in this article is cited from Sahih Muslim.