Another very important characteristic of the Islamic calendar is that it contains four sacred months, as Allah says:

إِنَّ عِدَّةَ ٱلشُّهُورِ عِندَ ٱللَّهِ ٱثْنَا عَشَرَ شَهْرًا فِى كِتَـٰبِ ٱللَّهِ يَوْمَ خَلَقَ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضَ مِنْهَآ أَرْبَعَةٌ حُرُمٌ ۚ ذَٰلِكَ ٱلدِّينُ ٱلْقَيِّمُ ۚ فَلَا تَظْلِمُوا۟ فِيهِنَّ أَنفُسَكُمْ ۚ وَقَـٰتِلُوا۟ ٱلْمُشْرِكِينَ كَآفَّةً كَمَا يُقَـٰتِلُونَكُمْ كَآفَّةً ۚ وَٱعْلَمُوٓا۟ أَنَّ ٱللَّهَ مَعَ ٱلْمُتَّقِينَ

“The number of months ordained by Allah is twelve in the Book of Allah since the day He created the heavens and the earth. Of these, four are sacred; that is the established principle of Deen. Therefore, do not wrong yourselves by violating them. But you may fight against the mushrikeen in all these months if they fight against you in all of them. Know that Allah is with the righteous.” [At Tauba: 36]

In addition, the Prophet ﷺ said:

السَّنَةُ اثْنَا عَشَرَ شَهْرًا مِنْهَا، أَرْبَعَةٌ حُرُمٌ، ثَلاَثٌ مُتَوَالِيَاتٌ، ذُو الْقَعْدَةِ وَذُو الْحِجَّةِ وَالْمُحَرَّمُ وَرَجَبُ مُضَرَ الَّذِي بَيْنَ جُمَادَى وَشَعْبَانَ

….. the year is twelve months, four of which are sacred. Three of them are in succession: Dhūl-Qaʿdah, Dhūl-Ḥijjah, Muḥarram, and [the fourth being] Rajab Muḍar, which stands between Jumādá [Thāniyah] and Shaʿbaan. [Sahih al-Bukhari 4662]

Numerous approaches have attempted to uncover the wisdoms behind the sanctity of the four sacred months, but at its core, sanctity stems from Allah’s divine choosing. Hadhrat Qatāda (rahimahullah) surmises:

Allah glorifies whatever He wills. Allah chose a select few from His creation, chose certain angels and humans to be messengers, chose certain words to be mentioned, chose specific lands to be places of worship, chose the month of Ramaaan [as the month to fast] and chose the sacred months… So glorify what Allah has glorified for things are only glorified because Allah has glorified them, [and this is understood] by those with acumen and intellect.

Understanding the wisdom behind what Allah has commanded helps the feeble human mind attain deeper appreciation; however, understanding the wisdom behind a particular command is not a prerequisite for the command to be obeyed. For example, there may be wisdoms for why we perform three rakʿah for the maghrib (sunset) prayer, but regardless of whether we understand those wisdoms, the responsibility of performing the prayer the way it has been mandated emanates from the command of the Prophet ﷺ, whom Allah ordered us to obey. Similarly, the sanctity of the sacred months comes from Allah’s divine choosing. A person may choose to express gratitude for this in different ways and extract various wisdoms as a means of motivation, but must be cautious not to claim these wisdoms as their reasons for obedience. Ultimately, glorifying the sacred months is part of obeying Allah’s commands.