Is the statement attributed to Imam Ali (may Allah be pleased with him) authentic: "Whoever complains to a believer has complained to Allah, and whoever complains to a disbeliever has complained about Allah"?

The authenticity of the saying, "Complaining to other than a believer is a humiliation," attributed to Imam Ali, has not been established; it is an incorrect statement, as complaining to a believer is not equivalent to complaining to Allah. Islamic law has enjoined complaining to Allah alone and supplicating to Him, and has forbidden complaining to others. Allah Almighty said, quoting Jacob (peace be upon him): "I only complain of my suffering and my grief to Allah," and about Khawlah bint Tha'labah: "and she was complaining to Allah."

Scholars have clarified that complaining to other than Allah is a humiliation, and that the gnostic complains to Allah alone. The most knowledgeable of gnostics is he who directs his complaint to Allah concerning himself, not concerning people, citing His (Exalted is He) saying: "And whatever strikes you of disaster - it is because of what your hands have earned." There are three levels of complaining: the lowest is complaining about Allah to His creation, the highest is complaining about oneself to Him, and the middle is complaining about creation to Him.