Rabi al-Thani

Rabi al-Thani is the fourth month of the Islamic (Hijri) calendar, its name meaning the second spring, paired with the preceding Rabi al-Awwal from the season the lunar names once marked. It is not among the four sacred months and carries no major prescribed festival, though particular communities keep commemorations of saints and teachers within it. The Islamic calendar is purely lunar, its twelve months following the phases of the moon and its year of about 354 days making no adjustment to the solar year, so the months move about eleven days earlier through the solar seasons each year and the springtime names no longer match the actual season. These are the features of the Islamic calendar tradition, in which Rabi al-Thani follows the month associated with the Prophet's birth.

Rabi al-Thani, meaning the second spring, is the fourth month, its name, like Rabi al-Awwal's before it, inherited from the seasonal terminology of the pre-Islamic Arabian calendar rather than describing the month's actual season under the fixed, purely lunar Islamic calendar in use since the Quranic prohibition of intercalation. The month is also sometimes called Rabi al-Akhir, the last or final Rabi, a naming variant found across different regional and historical Islamic sources without a difference in meaning. Rabi al-Thani carries no major fixed religious observance shared broadly across the Muslim world, unlike the sacred months and the two months of Ramadan and Dhu al-Hijjah that surround the annual cycle of fasting and pilgrimage.

The name is glossed as the second spring. It is not one of the four sacred months. The twelve month names are Arabic and predate Islam, retained from the calendar of the Arabian peninsula when the Hijri reckoning was established.

Four of the twelve are the sacred months, al-ashhur al-hurum, in which warfare was forbidden in pre-Islamic Arabia and which the Quran confirms at sura 9 verse 36: Dhu al-Qadah, Dhu al-Hijjah, Muharram and Rajab. Three run consecutively and the fourth stands alone in the middle of the year, an arrangement that fitted the pilgrimage season and the trading truces that went with it.

The Hijri calendar admits no intercalation. The verse immediately following the one that names the twelve months condemns nasi, the pre-Islamic practice of postponing or adding a month, and the calendar has run as a strict lunar reckoning since. The consequence is a year of 354 or 355 days that moves against the seasons by about eleven days annually, so any month passes through the whole solar year in roughly thirty-three years.

Rabi al-Thani completes the pair begun by Rabi al-Awwal. Four of the twelve names come in such pairs, the two Rabis and the two Jumadas, which is one of the marks that the list was assembled as a seasonal calendar before the prohibition of intercalation detached it from the seasons.