Shaykh Salih al-Fawzan explains that during the time of the Prophet ﷺ people used to say, “Allah ﷻ and His Messenger ﷺ know best.” After the Prophet ﷺ passed away, this phrase is no longer used. Instead, when someone does not know something—whether it is about religion or worldly matters—they should simply say, “Allah ﷻ knows best.”
“Does a person in a state of ignorance (today) say “Allāh ﷻ and His Messenger ﷺ know best” and is this (only) said regarding matters of the religion or can it (also be) said regarding worldly affairs?”
“This used to be said when the Messenger ﷺ was alive. It would be said “Allāh ﷻ and his Messenger ﷺ know best.” When the Messenger ﷺ died, it was then said: “Allāh ﷻ knows best.”
(He should) say “Allāh ﷻ knows best” in everything which he doesn’t know, whether in the matters of the religion or worldly. Everything he doesn’t know then he should say: “Allāh ﷻ knows best.”
