The Muslims conquered Mecca in 8 A.H. (after the migration of Prophet Mohammad PBUH&HP from Medina to Mecca) and made the city a major part of the Islamic rule. The non-believers, however, continued to live in the city and practice their own rituals. They were even allowed to carry out their idol worshipping practices during the Hajj period. In 9 A.H., things changed after the revelation of a verse from the Holy Quran chapter, Al-Tawbah. This verse was an ultimatum for non-believers in that they had 4 months to decide whether to stay in Mecca and convert to Islam or leave Mecca for good. Thus, the messenger of Allah (PBUH&HP) had the mission to convey this message to everyone on the Eid al-Adhha, which marked the centerpiece of the whole ceremony.
Amir al Mumenin Ali (PBUH) was sent to convey this message; he situated himself amongst the people practicing the rituals and said: “Oh people I am sent here by the messenger of Allah to read you the following revealed verses: “….so the non-believers have the opportunity to be in this city for another four months … and no non-Muslim will be allowed to visit the house of Allah after this year; any deal with the Prophet will also end at the end of the four months as well.”
Since then Muslims have been the only ones to perform the pilgrimage of the House of Allah. Every Muslim entering this journey will most certainly face some hardship along the way, which is why Allah has considered special rewards for the pilgrims. One of such rewards is the mercy Allah has placed for the pilgrims; for example, “upon performing the shaving of the head ritual (in Hajj) on the day of Eid al-Adha, a pilgrim will written up for his sins in the next forty days.” When people asked the Imams about the reasoning behind this issue, the Imams referred to the non-believer example expressing, “Allah (SWT) gave four months to the non-believers to freely come and go (during this period). He gave the people who did not accept Allah as the creator of the universe full immunity and safety. How could he not give immunity to the people who worship Him on a daily basis (Muslims) and who are in fact His guests at this house? Therefore, Allah forgives those sins not performed on purpose.
Selection taken from the Interpretation of Surah al-Tawbah by Ayatullah Ziabadi (with minor changes)
Congratulations to all Muslims and especially you dear friend
on the auspicious occasion of the Eid al-Adha
A time of freeing oneself from all chains, and attaching oneself to the Giver of Life