Is the Messenger's pleasure as important as Almighty Allah's pleasure, or is obedience to the Messenger as important as obedience to Allah? And will what happens in the Hereafter be by Allah's will? And is it permissible to say: "There is no Most Merciful but Allah" or "There is no Oft-Pardoning but Allah"?

Obeying the Messenger (peace and blessings be upon him) and pleasing him are duties, just as obeying and pleasing Allah Almighty are duties. They are equal in obligation and importance. This is indicated by Allah Almighty’s saying: "He who obeys the Messenger has obeyed Allah," and by the Prophet's (peace and blessings be upon him) saying: "All of my Ummah will enter Paradise except for those who refuse." It was asked, "Who are those who refuse, O Messenger of Allah?" He said, "Whoever obeys me will enter Paradise, and whoever disobeys me has refused."

As for the saying "there is no Rahman (Most Merciful) except Allah" or "there is no Tawwab (Acceptor of Repentance) except Allah," there is no harm in it, because it signifies monotheism.