A hadith qudsi ("sacred" or "divine" hadith) is distinguished from an ordinary hadith by where its meaning is held to originate: scholars such as al-Jurjani describe it as conveying the words of God, expressed through Muhammad's own wording, in contrast to the Qur'an, whose wording itself is held to be God's. That distinction is about standing, not soundness — a hadith qudsi need not be sahih (sound); some classed this way are da'if (weak) or disputed, judged by the same chains-of-transmission criteria as any other hadith.
Gathering forty hadith qudsi follows the same old habit as [[NAW|al-Nawawi's Forty Hadith]] and the wider "forty hadith" (arba'iniyyat) genre it belongs to, narrowed here to one category of hadith rather than hadith in general. A widely circulated English edition under this exact title — selected and translated by Ezzeddin Ibrahim and Denys Johnson-Davies, who also produced the companion translation of al-Nawawi's collection — was published by the Islamic Texts Society in 1997 as a bilingual Arabic/English volume, drawing its forty hadith from across the classical hadith literature. Whether the forty hadith served by this corpus are that same selection, or an independently assembled set published under the same traditional title, has not been established on this corpus's side.
The Arabic text here is the classical matn, held to be in the public domain. Beneath it in the reader sits an English translation, drawn from the fawazahmed0/hadith-api's eng-qudsi edition and aligned hadith-for-hadith with the Arabic so the two can be read as a pair — the same companion arrangement this corpus uses for [[BUK|Sahih al-Bukhari]], [[MUS|Sahih Muslim]], [[ABD|Sunan Abi Dawud]], [[TIR|Jami` at-Tirmidhi]], [[NAS|Sunan an-Nasa'i]], [[IBM|Sunan Ibn Majah]], [[MAL|Muwatta Malik]], [[NAW|Forty Hadith of an-Nawawi]], and its Qur'an translations. Which published English translation this file itself descends from has not been pinned down on this corpus's side, which is why its licence is marked under review rather than public domain outright; the Arabic above it carries no such uncertainty.