What is the wording of the salutation upon the Prophet (peace and blessings be upon him) in the tashahhud?

Question:
It was narrated from Ibn Mas'ud (may Allah be pleased with him) that he said: "We used to say in the tashahhud during the lifetime of the Prophet (peace and blessings be upon him): 'Peace be upon you, O Prophet, and the mercy of Allah and His blessings.' And after his passing, we used to say: 'Peace be upon the Prophet, and the mercy of Allah and His blessings.'" Is this correct? And do we say it in the tashahhud?

Answer:
What is prescribed is that we say what the Prophet (peace and blessings be upon him) taught his companions. He taught them to say: , so we say what the Messenger (peace and blessings be upon him) taught the Companions. He did not say to them: "When I die, change it." He taught them, while they were traveling to distant lands, to say: , meaning: they supplicate for him. So is a supplication for him for safety, mercy, and blessings, and means: invoking the presence of the Prophet; it does not mean that they are calling upon him. And their saying means: for you is safety, and for you is well-being, mercy, and blessings from your Lord. It is a supplication for the Prophet (peace and blessings be upon him), not that he is being called upon. Rather, you are asking Allah for him for safety, mercy, and blessings.
And whoever says: "Peace be upon the Prophet, and the mercy of Allah and His blessings," there is nothing wrong with it. But it is better to say what the Prophet (peace and blessings be upon him) taught the Companions: . This is what the Prophet taught his Ummah, and he died upon it, may Allah's prayers and blessings be upon him.