Introduction
With the emergence of Islam, religious architecture gained significant importance, and the mosque became the successor to previous places of worship (Zomarshidi, 1995, p. 9). This shift has played a crucial role in the significance of congregational mosques, making them stand out even more than other mosques in terms of decorative inscriptions (Sedaghat, 2008, pp. 19-18). These inscriptions reflect the architectural transformations of mosques as well as document significant cultural, economic, social, and political events throughout various eras, providing valuable information. This article discusses and recognizes the architecture and inscriptions of the Congregational Mosque of Qaen, which is one of the important mosques from the Timurid period in South Khorasan Province. A review of previous research reveals that there has been no comprehensive study focused on the architecture, inscriptions, decorations, and formation of the Congregational Mosque of Qaen. Therefore, considering the importance of this building, conducting more thorough and complete research on it will not only clarify its characteristics but also enhance our understanding of the culture and architecture of Khorasan. The main questions of this research are:

What time period is covered by the inscriptions used in the Congregational Mosque of Qaen?
What subjects are encompassed in the content of these inscriptions?

 
Architecture of the Congregational Mosque of Qaen
The Congregational Mosque is a two-iwan rectangular structure. The entrance iwan is located on the eastern side. Beyond the entrance iwan is the courtyard, where, on the opposite side of the entrance, another iwan and a prayer hall (shabestan) can be seen. On both the northern and southern sides, there are small iwans with a depth of two meters flanking the entrance iwan on the east side of the building. In part of the courtyard, there is a sundial as well as a water reservoir (payabi). The main iwan of the mosque, situated on the southwest front of the building, is a masterpiece of architecture, with two prayer halls constructed on either side. The decorations used in this iwan include brickwork on the main facade, featuring both horizontal and vertical patterns with geometric designs, while the surfaces below the ceiling of the iwan are adorned with geometric and arabesque patterns, as well as muqarnas. A total of 15 inscriptions have been identified in this mosque, the oldest of which, dating back to 796 AH, is located inside the main iwan and contains an Arabic text stating that the order to construct the mosque was given by Jamshid ibn Qaran ibn Jamshid ibn Ali ibn Ashraf ibn Qazi Shams al-Din Ali al-Qayeni in the year 796. The inscription reads:
“This construction has been undertaken as a charity for the sake of God by the humble servant of God, Nizam al-Haqq wa al-Din Jamshid ibn Qaran ibn Jamshid ibn Ali ibn Ashraf ibn Qazi Shams al-Din Ali al-Qayeni in the months of the year 796.”
Inscriptions number 2, dating to 921 AH, concerns the collection of taxes from the people. Inscription number 3 is dated 1046 AH and pertains to a trust of water from a qanat for the mosque. Inscription number 4, also from the year 1046 AH, discusses tax exemptions for certain segments of the population. Inscription number 5 relates to repairs made to the mosque during the reign of Shah Suleiman Safavi in 1098 AH by Haji Muhammad Hossein. Inscription number 6 pertains to the construction of a wooden pulpit for the mosque, dating to 1082 AH. The subsequent inscriptions are from the Qajar period, starting from 1246 AH and continuing to the most recent one, which dates to 1993. These inscriptions, written with ink and color on plaster and mostly found beneath the iwan, include the names of the master builder, the painter, and the scribe, as well as prayers and poems commemorating the significance and grandeur of the mosque. The last inscription (number 15) is related to a tombstone that is placed on the outer wall next to the entrance iwan on the western side of the mosque.
 
Findings
Construction Inscriptions: The inscription labeled Number 1, which indicates the construction of the building, and inscription Number 6 (the pulpit) are classified as construction inscriptions. These two inscriptions are historically significant because they specify not only the date of construction but also the names of the founder, builder, and artist.
Endowment Inscriptions: An examination of the endowment inscriptions reveals the religious thoughts of the people. Inscription Number 3 states that land should be cultivated, and its proceeds are to be endowed to the mosque. At the end of the inscription, prayers are offered for the king and the owners, along with a curse on anyone who alters the endowment.
Governmental Inscriptions: Another category of common themes in the inscriptions includes government orders and decrees that were installed in buildings for public awareness. Inscriptions Number 2 and 4 fall under this category. Inscription Number 2 also features Persian words alongside verses from the Quran. Perhaps the inclusion of a Quranic verse served to bless and confer respect upon that inscription, thus preventing its destruction.
Restoration Inscriptions: The oldest of these inscriptions is Number 5, which begins with a portion of verse 18 from Surah At-Tawbah. Inscription Number 7 was written during the restoration of the building by Karbala’i Ishaq Qayeni. Inscription Number 8 is also related to the restoration, placed within a floral frame with two other inscriptions on either side, containing poetry written by Gholamreza Zaker about the majesty of the mosque’s arch. Inscription Number 9 concerns the restoration of the building and contains verses praising the greatness of the mosque. Inscription Number 14 is the most recent restoration inscription in the mosque.
Prayer Inscriptions: In addition to the use of Quranic verses in the inscriptions, there is a group that contains written prayers. Inscriptions Number 11, 12, and 13 are part of the prayer inscriptions, created during the Qajar period and featuring red and black ink on plaster.
Narrative Inscriptions: In the Congregational Mosque of Qaen, inscriptions Number 7 to 10 belong to this category. Inscription Number 7 contains a stanza from a poem in Saadi’s Gulistan. Inscription Number 10 features a poetic line emphasizing the importance of prayer. Inscription Number 8 is a stanza describing the grandeur of the mosque's iwan, spiritually comparing it to Al-Aqsa Mosque. Inscription Number 9 describes the vastness of the mosque's iwan using the literary device of exaggeration. The tombstone inscription Number 15, located at the entrance iwan on the western side of the mosque, includes verses related to the Day of Resurrection, though much of the text has become illegible due to weathering.
Conclusion
The inscriptions of the Qaen Mosque can be divided into two groups based on their temporal context: the first group pertains to the Timurid and Safavid periods, consisting entirely of stone inscriptions related to the construction of the building, government orders, endowments, religious objectives, and restorations of the mosque. The second group is later and primarily associated with the Qajar period, focusing on the restoration of the building and encompassing the area beneath the southern dome chamber.
The studied inscriptions, alongside governmental and restoration texts, include Quranic verses, prayers, names of God, the Prophet, Imams, as well as the names of craftsmen such as the architect, stonecutter, painter, and endower. Understanding these inscriptions is particularly important for identifying the art and local artists throughout various historical periods. The inscriptions from the Safavid period hold significant value, not only for their aesthetic aspects but also as indicators of the political, social, economic, cultural, and religious conditions of that era.