The Muslim year is based upon a lunar cycle of 354 days, consisting of 12 months of 29 or 30 days. This calendar commenced in the year 622 of the common era (C.E.), when the beloved Prophet Muhammad (Allah bless him and give him peace) migrated from Mecca to Madina.

Virtues of Islamic Months and Recommended Prayers Printed on the occasion of 74th Urs of Alahazrat Imam Raza Khan Qadiri
1: Muharram	2: Safar	3: Rabi al-Awwal	4: Rabi ath-Thani
5: Jumada al-Ula	6:Jumada al-Akhirah	7: Rajab	8: Shabaan
9: Ramadaan	10: Shawaal	11: Dhul Qadah	12: Dhul-Hijah

Shaikh Sayyiduna Abdul Qadir Jilani (May Allah be pleased with him) has mentioned in his discourse that Almighty Allah (Exalted is He) sent down the revelation: "The number of months in sight of Allah is 12 months. These months were already inscribed in the "Book of Almighty Allah", that is, on the Well-Kept Tablet [al-lawh al-Mahfuz] – "on the day when He created the heavens and the earth; four of them are sacred…" The names of the sacred 4 months referred to are: Rajab, Dhul Qada, Dhul Hijja, and Muharram. One of these sacred months stands in isolation, namely Rajab, while the other 3 occur in consecutive sequence (in accordance with Islamic calendar). [Rajab is the 7^th month of the Islamic calendar while, Dhul Qada, Dhul Hijja and Muharram are the 11^th, 12^th and 1^st months respectively.]

As for the sentence: "Do not wrong yourselves in them", the meaning is: "…in the sacred months." Almighty Allah (Exalted is He) has applied this prohibition to these 4 months specifically, in order to make us clearly understand that they deserve particular respect because of the magnitude of their holiness. In other words, it is in order to emphasize their special importance that He mentions them explicitly, rather than any of the other months, in connection with the prohibition of wrong doing, although wrong doing is actually forbidden during all the months of the year. [Sufficient Provision for Seekers of the Path of Truth al-Ghunya li-Talibi Tariq al-Haqq, Volume 3, 5^th-12 discourse explains the virtues of the different months of the Islamic calendar.]

Imam Ahmad Raza (May Allah be pleased with him) explained that there is wisdom in fixing specific dates of the Urs of the Saints (Auliya) because on the day of their Wisaal (death), their souls have greater concentration in the respected graves; hence, this is a perfect time to derive the bounties of Rahmah from them. This corresponds to Sayyiduna Abdul Qadir’s Jilani (May Allah be pleased with him) prayer taken from his discourse [al-Ghunya…] which has a note appended to it explaining that the saints are on different days of the month at different points of the compass, a matter, which, with knowledge and care, can be arranged for in addressing them. [Padwick – Muslim Devotions]