إِنَّ عِدَّةَ الشُّهُورِ عِنْدَ اللَّهِ اثْنَا عَشَرَ شَهْرًا فِي كِتَابِ اللَّهِ يَوْمَ خَلَقَ السَّمَاوَاتِ وَالْأَرْضَ مِنْهَا أَرْبَعَةٌ حُرُم
Inna ‘iddatash-shuhūri ‘indallāhi-thnā ‘ashara sharan fī kitābi-llāhi yawma khalaqas-samāwāti wal-ardha minhā arba‘atun hurum
Indeed the number of months with Allah is twelve months in Allah’s Book, the day when He created the heavens and the earth. Of these, four are sacred. (Sūratut Tawbah, No. 9, Āyat 36)
Since the beginning of creation, Almighty Allah set a system for it to help human beings keep track of time and organize their lives. So the heavens and earth were created such that the earth revolved around its axis, and also rotated around the sun. This brought about days and nights, and these added up to months, twelve of which formed a year.
Aghae Muhsin Qarā’ati mentions in Tafsīre Nūr that twelve is a blessed number. It is the number of the chiefs of the Banū Israel (5:12), and the number of springs that gushed out for each of the twelve tribes of the Banū Israel (2:60). Twelve is also the number of Divine leaders – Imams – after the Holy Prophet (s).
Abdullah Yusufali states in his Commentary that the Pagan Arabs changed the order of the sacred months by adding or deducting months in a year in order to have an unfair advantage over their enemy. This āyat condemns this arbitrary and selfish conduct during the pre-Islamic age of Ignorance (jāhiliyyah).
The four scared months mentioned in the verse above are: Rajab, Dhulqa‘dah, Dhul Hijjah, and Muharram. No fighting was allowed in these sacred months, and Muslims were told to revere the sanctity of these months. Out of these, the first one is the holy month of Rajab, the beginning of a spiritual season of worship and closeness to God. As the Holy Prophet (s) says: Rajab is the month of Allah, Sha‘bān is my month, and Ramadhān is the month of my Ummah.
The month of Rajab is a symbol of the love of God for His creatures, where He invites and encourages them to seek forgiveness, fast, and worship more intensely. In this lies their success through His pleasure. Imam Zaynul ‘Ābidīn (a) says:
So they remember You for Your kindness
they thank You for Your Blessings
they pray to You by Your command
and they donate for You in order to seek Your increase
In all this lies their deliverance from Your wrath
and their triumph through Your good pleasure (Al-Sahīfa al-Sajjādiyyah, Du ‘ā 45, Passage 16)
Use the opportunity during this sacred month to elevate your status in the eyes of Allah, and gain a peace and satisfaction that can only come from a close connection to Him. The famous manual of devotion Mafātīh al-Jinān contains numerous acts of devotion (a‘māl) to be performed in Rajab. It is also essential that we revere the sanctity of Islamic days (e.g. Friday), months (e.g. Ramadhān), structures (e.g. masājid), Book (e.g. the Qur’an), names (e.g. Muhammad), practice (e.g. saying salām to each other), etc. without changing them to suit our whims.
Sources: Imam Ali Zaynul ‘Ābidīn (a), Al-Sahīfa al-Sajjādiyyah; Aghae Muhsin Qara’ati, Tafsīr-e Nūr; Abdullah Yusufali, The Holy Qur’an: Text, English Translation and Commentary