Who should a muslim rely on as a sustainer?

Generally speaking, a Muslim has to believe that Allah is the one Who sustains him/her, and He is only the One Who could harm or benefit him/her. There are many Qur’anic verses and hadiths prove this fact. For example, Almighty Allah says, “Say: I have no power to hurt or benefit myself, save that which Allah willeth…” (Yunus: 49)

Also, the Prophet (peace and blessings be upon him) is reported to have said, “Be mindful of Allah, and you will find Him in front of you. If you ask, ask of Allah; if you seek help, seek help of Allah. Know that if the Nation were to gather together to benefit you with anything, it would benefit you only with something that Allah had already prescribed for you, and that if they gather together to harm you with anything, they would harm you only with something Allah had already prescribed for you…” (Reported by At-Tirmidhi)

Furthermore, a Muslim has to believe that no one except Allah could know the unseen. The Qur’an says, “Say (O Muhammad): None in the heavens and the earth knoweth the Unseen save Allah…” (An-Naml: 65)