Can the Prophet's supplication, peace be upon him, ever be rejected or unanswered sometimes, as in His, the Almighty's, saying: "Whether you ask forgiveness for them or do not ask forgiveness for them"?

The Prophet's supplication is generally answered, though it might not be answered in a specific matter, such as his supplication that the might of his community not be among themselves. Muslim narrated that he (peace be upon him) said: "I asked my Lord for three things, and He granted me two and withheld one. I asked my Lord not to destroy my community by famine, and He granted it to me. I asked Him not to destroy my community by drowning, and He granted it to me. I asked Him not to make their might among themselves, and He withheld it from me."

The answering of a supplication is not limited to the exact request; rather, it occurs in one of three ways: either his supplication is hastened for him, or it is stored for him in the Hereafter, or an equivalent evil is averted from him.