What is the authenticity and explanation of the Hadith: "You must fear Allah as much as you can, and remember Allah at every stone and tree, and whatever evil deed you have done, make an immediate repentance to Allah for it: the secret by the secret, and the public by the public"? And does it mean that repentance for a secret sin should be secret, and is repentance in the mosque sufficient for one who has sinned secretly?

The Hadith (definition) encourages piety towards Allah as much as one is able, and to remember Him at all times and in every state, and to hasten to repentance immediately without procrastination. If the sin was committed secretly, then repentance should be secret, by increasing regret, seeking forgiveness, and performing righteous deeds. However, if it was public, then repentance should be public, such that the servant demonstrates his repentance before people, to remove any ill suspicion about him and so that no one follows his example in his disobedience, and for it to be an impetus for others to repent. Repentance is not merely verbal; rather, the repentant person must demonstrate righteous deeds that contradict his former ways. It is also recommended for one who repents to perform ablution and pray the prayer of repentance.