His birth date is not known. There are several theories about his birthplace. According to Kayseri Ansiklopedisi, he was born in the village of Tırafşın, now called İncili of Tomarza District in Kayseri Province.
His fıkras (jokes) were collected by Süleyman Tevfik (Zorluoğlu) at the first time in the early Republican period. According to Abdülbaki Gökpınarlı, Çavuş's treatise, that had been addressed to Sheikh ul-Islam at the time and written in both Arabic and Turkish languages, was found in Kayseri in 1933-1934. In two small treatises in a volume, it was mentioned that the name of Muhammad were passed in the Bible (Turkish: İncil). In this way, they gave him the nickname "İncili".
As to another tale, Sultan Suleiman the Magnificent (reigned 1520–1566) was very pleased with Mustafa's showing extraordinary proficiency in an archery contest that was participated by his princes, and said to Mustafa, "I'm giving you the rank of a Çavuş (sergeant). And to be able to distinguish you from other sergeants and to show your superiority over others, I'm attaching a pearl to your turban." After this affair, his name Mustafa was forgotten and he began to be called "İncili".
According to Mustafa Enhoş, he was referred in the History of Naima as a sergeant of the Dergâhı Âlî in 1615. According to Sennur Sezer and Adnan Özyalçıner, he was one of Musahibs of Sultan Ahmed I (reignrd 1603–1617) and was sent to Safavid Persia as part of the Ottoman delegation (elçi). According to Kayseri Ansiklopedisi, some sources recorded that he accompanied İbrahim Çavuş, who was sent to Iran as ambassador, as "selam çavuşu" in 1626.
- Çavuş means: 1. a title given to the officials who engaged in various services provided of in the organizations of the Ottoman State, 2. a rank of officers who were responsible for transmitting down orders of senior commanders subordinate commanders in the Ottoman Army. çavuş in BSTS / Tarih Terimleri Sözlüğü, 1974. (Turkish)
- Warren S. Walker, Ahmet Edip Uysal, More Tales Alive in Turkey, Texas Tech University Press, 1992, ISBN 978-0-89672-286-6, p. 305.
- Türk Kültürü Onsekizinci Yıl, Türk Kültürünü Araştırma Enstitüsü, 1979, p. 313. (Turkish)
- Abdullah Satoğlu, Kayseri Ansiklopedisi, Kültür Bakanlığı, 2002, ISBN 978-975-17-3009-1, p. 185. (Turkish)
- Osman Sak, İrfan Çalışkan, Tarihi, Kültürü ve Sanatıyla Eyüpsultan Sempozyumu, VII: Tebliğler, Eyüp Belediyesi Kültür ve Turizm Müdürlüğü, 2003, ISBN 978-975-93844-2-5, p. 311. (Turkish)
- Mustafa Enhoş, Bütün yönleriyle Akseki ve Aksekililer, Hüsnütabiat Matbaası, Antalya, 1974, p. 130. (Turkish)
- Sennur Sezer, Adnan Özyalçıner, İstanbul'un Taşı-Toprağı Altın: Eski İstanbul Yaşayışı ve Folkloru, Altın Kitaplar Yayınevi, 1995, p. 235. (Turkish)
- Murad dönemlerinde Saray'da bulunduğu, 1626 yılında İran'a elçi olarak gönderilen İbrahim Çavuşun yanına "selam çavuşu" olarak katıldığı, bazı kaynaklarda kaydedilmektedir., Kayseri Ansiklopedisi, p. 185.
- Türk Kültürü Onsekizinci Yıl, Türk Kültürünü Araştırma Enstitüsü, 1979, p. 314. (Turkish)
- İncili Çavuş, İncili Çavuş'un Güzel Resimli Lâtifeleri, Bozkurt Kitap ve Basımevi, 1945. (Turkish)
- Dursun Yıldırım, Türk Edebiyatında Bektaşi Tipine Bağlı Fıkralar: İnceleme-Metin, Kültür Bakanlığı, 1976. (Turkish)
- Tahir Galip Serʼatlı, Mizahımızın Üç Ustası: Nasreddin Hoca, İncili Çavuş, Bekri Mustafa, Selis, 2004, ISBN 978-975-8724-35-2. (Turkish)