Is it permissible for the reciter to say, "may Allah bless him and grant him peace," after reciting, "Muhammad is the Messenger of Allah; and those with him," seeking a blessing from the Hadith where the Prophet cursed anyone whose name was mentioned and did not invoke blessings upon him?

The Prophet, peace and blessings be upon him, did not curse whoever mentioned his name and did not send blessings upon him. Rather, he said: "The stingy one is he by whom I am mentioned, and he does not send blessings upon me." It is recommended for whoever reads a verse containing the name of the Prophet, peace and blessings be upon him, to send blessings upon him.