What is the interpretation of Allah's saying: "O you who have believed, fear Allah, your Lord," from Surat An-Nisa, in Sahih Muslim or Al-Bukhari?

Perhaps the questioner is referring to the first verse of Surat An-Nisa (Chapter of Women): "O mankind, fear your Lord, who created you from one soul and created from it its mate and dispersed from both of them many men and women." This is because the phrase "O you who have believed, fear your Lord" does not exist in the Quran. This verse is Medinan, and the statement of some scholars that the address in Medinan chapters was "O you who have believed" is not absolute, as the Medinan Surah (definition) Al-Baqarah (The Cow) contains "O mankind." The address "O mankind, fear your Lord" is a divine command from Allah to all His servants to fear Him, which means obeying His commands and avoiding His prohibitions, in secret and in public. It includes all accountable individuals until the Day of Judgment.