Allah Almighty has said, "Surely the number of months with Allah is twelve in Allah's ordinance since the day He created the heavens and the earth, of these four are sacred; that is the right reckoning; therefore, do not be unjust to your own selves regarding them (Holy Qur'an, 9:36)." These are the lunar months upon the reckoning of which does a Muslim in the east of the earth or the west rely; chronologically arranged, they are as follows: 1) Muharram, 2) Safar, 3) Rabi' I, 4) Rabi' II, S) Jumada I, 6) Jumada II, 7) Rajab, 8) Sha'ban, 9) the month of Ramadan, 10) Shawwal, 11) Thul-Qi'da, and 12) Thul-Hijja. According to astronomy, the lunar calendar cannot be less than 29 days, nor can it be more than 30. It may once be 29 days and another 30, and its average is 29 days and 12 hours and five minutes. The beginning of each lunar month is recognized by the sighting of the new moon, the crescent. The Almighty says, "They ask you concerning the new moons. Say: They are times appointed for the benefit of men, and for the pilgrimage" (Holy Qur'an, 2:189).
In this verse, the Almighty has explained to us how to calculate and determine time by mentioning the word ahilla, which is the plural of the Arabic singular hilal, crescent, when it becomes visible to the naked eye. These crescents set the time for people and help them determine when the pilgrimage is to be performed.
Fast of the month of Ramadan
The lunar calendar of Islam brings the fast of the month of Ramadan eleven days earlier every year. Thus, in a cycle of about thirty-three years, it passes through all the seasons successively. Fast was first prescribed on the second of Sha'ban in the second year of Hijrah (the migration of Prophet Muhammad, peace and blessings of Allah be upon him and his progeny, from Mecca to Medina, corresponding to 622 A.D.).
On p. 59, of al-Saduq's Amali (or Majalis), the faqih mentor and author quotes Ja'fer ibn Ali ibn al-Hassan ibn Ali ibn Abdullah ibn al-Mughirah al-Kufi as saying that his grandfather al-Hassan ibn Ali quotes his grandfather Abdullah ibn al-MugIurah quoting Isma'eel ibn Abu Ziyad quoting Abu Abdullah Imam Ja'fer ibn Muhammad al-Sadiq (as) citing his forefathers, peace be upon all of them, saying that the Messenger of Allah (pbuh)' once asked his companions,
Shall I tell you about something which, if you do it, will distance you from Satan as much as the distance between the east and the west?" They said, "O yes! Please do so," whereupon he (pbuh) said, "It is fast. It darkens his [Satan's] face, while charity breaks his back and the love for Allah's sake and assisting others in doing good deeds cut off his tail and seeking Allah's forgiveness splits his spine. For everything there is a zakat (purification), and the zakat of the bodies is fast.
Fast of the month of Ramadan is the fourth pillar of Islam. The Arabic word shahr is used for a month due to its being mushtahir, well-known or famous, that is, the knowledge thereof reaches all people, as we are told by Imam Ibn Manzoor, author of Lisan al-Arab on p. 432, Vol. 4. Such knowledge can be attained by sighting its crescent. As to the reason why it has been called the month of Ramadan, it is due to the fact that the Arabs gave the names of the months according to the times during which they occurred, and to the fact that it so happened that the month of Ramadan coincided with the parching days of the summer. Its root word ramd, as the same author tells us on pp. 160-161, Vol. 7, of the same lexicon, means to burn due to excessive sun-heat reflected on the desert sands. The ramda is the burning rock. This is why it was called the month of Ramadan. One may say in Arabic that a man's feet were burnt due to the heat, so he became ramad. It is also said that it was called the month of Ramadan because people become ramad due to their suffering from the combination of hunger and thirst during a very hot month. Arab linguists say that to make something armad is to squeeze it between two soft rocks then to pound it. A person fasting, by analogy, pounds his own nature between two rocks: hunger and thirst.
According to one of his numerous traditions, Prophet Muhammad (pbuh) is quoted saying, "The month of Ramadan was named so because it tends to ramad the sins, that is, burn them." The righteous at the dawn of Islam used to call it al-midmar, meaning that it emaciates the souls and bodies and helps them get rid of the excesses of evils and sins whereby the souls and bodies were laden. During the life-time of the Prophet (pbuh), the blessed month of Ramadan used to be called al-marzooq, the one full of sustenance, due to the abundance of the blessings of Allah whereby His servants are sustained during it.
In a letter he sent to Jarrah al-Madayini, Muhammad ibn Ya'qub cites Imam Abu Abdullah al-Sadiq (as) saying,
Fast is not only to abstain from eating and drinking. Then the Imam (as) quoted Mary (as) mother of Christ (as), as the Holy Qur'an tells us, saying that she had vowed a fast for the Most Merciful One. The Imam (as) continued to say, "When you fast, you should safeguard your tongues, lower your gaze, and you should neither dispute with nor envy one another.
This is recorded on p. 351, Vol. 94, of Bihar al-Anwar. The Imam (as) is also quoted in the same and following page of the said reference saying,
When you fast, let your hearing and vision abstain with you from anything unlawful, against everything ugly, and leave hypocrisy aside, and do not harm those who serve you. Rather, adorn yourself with the dignity of the fast, and do not make your fasting day any different from the day when you do not fast.
The Niyyat (Intention) to Fast
When the crescent is sighted in your area or country, a niyyat, that is, a silent declaration of intention, should be made to fast during this sacred month to attain nearness to Allah (wajib qurbatan ila-Allah). Just like the five daily prayers, the niyyat of fast is obligatory and mental, and so is the case of every deed according to Islam.