A ḥadīth (Arabic: حديث‎,  /ˈhædɪθ/ or /hɑːˈdiːθ/) (plural: hadith, hadiths, or aḥādīth) is a saying or an act or tacit approval or disapproval ascribed either validly or invalidly to the Islamic prophet Muhammad.

Hadith are regarded by traditional Islamic schools of jurisprudence as important tools for understanding the Quran and in matters of jurisprudence. Hadith were evaluated and gathered into large collections during the 8th and 9th centuries. These works are referred to in matters of Islamic law and history to this day. The two largest denominations of Islam, Shiʻism and Sunnism, have different sets of hadith collections.

In Arabic the word ḥadīth (Arabic: حديث‎ ḥadīṯ  IPA: [ħaˈdiːθ]) means 'a piece of information conveyed either in a small quantity or large'. The Arabic plural is أحاديث ʾaḥādīṯ/aḥādīth (IPA: [ʔaħaːˈdiːθ]). Hadith also refers to the speech of a person. As taḥdīṯ/taḥdīth is the infinitive, or verbal noun, of the original verb form; hadith is, therefore, not the infinitive, rather it is a noun.

Yusuf Estes (born in 1944) is an American Muslim preacher and teacher who converted from Christianity to Islam in 1991. He was a Muslim Chaplain for the United States Bureau of Prisons through the 1990s. He was a Muslim Delegate to the United Nations World Peace Conference for Religious Leaders held at the U.N. in September 2000.

Active in Islamic missionary work in the United States, Estes is often featured as guest presenter and keynote speaker at various Islamic events as well as frequently appearing on various Islamic satellite TV channels. Estes takes a dim view of today's public school system in the United States for any children, and highly recommends schools where they might receive a religious education combined with more advanced scholastic education.

Yusuf Estes was born in Ohio, and was raised in Houston, Texas in a Anglo-Saxon Protestant family. From 1962 to 1990, his career was in the music, entertainment and marketing fields. He also taught music and served as a music minister. He owned several musical instrument companies including the Estes Piano and Organ Company. He produced and directed live entertainment programs in the United States from the mid 1960s until his last endeavor for cable TV in Florida, entitled 'Estes Music Jamboree'.

Suhaib Webb is a contemporary American-Muslim educator, activist, and lecturer. He is currently the imam of the Islamic Society of Boston Cultural Center (ISBCC), the largest mosque in the New England area.

He was born William Webb in 1972 in Oklahoma to a Christian family, including a grandfather who served as a preacher. At age 14, he lost interest in religion going through a self-described spiritual crisis. He also began engaging in delinquency by joining a local gang, was involved in a drive by shooting, and became a successful local Hip-Hop DJ and producer, making records with various artists.

After converting to Islam in 1992, Webb left his career as a DJ and studied at the University of Central Oklahoma, where he graduated with a Bachelor's degree in Education. He also studied privately under a Senegalese Sheikh, learning enough Islam and Arabic to become a community leader in Oklahoma City, where he was hired as Imam at The Islamic Society of Greater Oklahoma City. He simultaneously started teaching at Mercy School, an Islamic K-12 school in Oklahoma City.

Adnan Oktar (born 1956), also known as Harun Yahya, is an author and Islamic creationist. In 2007, he sent thousands of unsolicited copies of his book, Atlas of Creation, which advocates Islamic creationism, to American scientists, members of Congress, and science museums. Oktar runs two organizations of which he is also the Honorary President: Bilim Araştırma Vakfı ("Science Research Foundation", BAV, established 1990), which promotes creationism and Milli Değerleri Koruma Vakfı ("Foundation to Protect National Values", established 1995) which claimed to promote Turkish nationalism. In the last two decades, Oktar has been involved in a number of legal cases, both as defendant and plaintiff.

Adnan Oktar was born in Ankara, Turkey, in 1956. He grew up in Ankara, and lived there through his high school years where he studied the works of Islamic scholars like Said Nursi, a Muslim Kurdish scholar who wrote Risale-i Nur, an extensive Qur'anic commentary which includes a comprehensive political and religious ideology.