AHL AL-TAHQÎQ - اهل التحقیق
Literally: Ahl is a man's family. A household. A kindred. Friends. People. A nation. A man's family and descendants. A wife. The people of a place, condition, profession, religion or quality. A person or thing closely related to some particular thing mentioned. A person who minutely ascertains the verities; a man of exact science.
Literally: Tahqîq is a making to be really existent. A giving real existence. A holding to be real and true. An affirming. An ascertaining. An investigating. Verifying: investigation, verification. A proving by irrefragable proof. To ascertain, verify, investigate. Investigating deeply, carefully and thoroughgoing. Investigation about something being truth or not.
Revealing the haqq or bâtil. Revealing the haqiqah.
Ahl Al-Tahqîq: The people of tahqîq. The ‘ulamâ who know haqiqahs with their proofs.
“Thus, foremost Bukhari and Muslim who are the authors of the six books of Hadith which are well-known with their authenticity agreed in the majority of those reports we will cite, and most of these reports are ma’nawî mutawâtir (متواتراً من حيث المعنى), and the others may be considered to have this certainty as mutawâtir through the agreement of their authenticity by ahl al-tahqîq.” The Nineteenth Letter-Fifth Subtle Sign
“The ijma of the Sahâbah, who were the people of justice on its occurrence and the agreement of all mufassirs who were ahl al-tahqîq on its occurrence in the tafsir of the âyah وَ انْشَقَّ الْقَمَرُ1 , and the transmission of its occurrence by all the muhaddisîn2 who were transmitters of the sound riwâyât through numerous authorities and different chains, and the testimony of all the awliyâ and the siddîqîn who were ahl al-kashf and ilham, and the confirmation of the erudite ‘ulamâ and imams of ‘ilm al-Kalâm, whose ways differ greatly from one another, and the acceptance of its occurrence by the ummah of Muhammad (asm) definitely who never agrees upon dhalâlah, prove the Splitting of the Moon as clearly as the sun.” The Thirty-First Word - Addendum to The Nineteenth Letter and Thirty-First Word, Fifth Point