How sound is the Hadith: "Every deed is between acceptance and rejection except for prayer upon me"?

The Hadith: "Every deed is between acceptance and rejection except for prayer upon me," has not been found, and it is highly likely that it is fabricated. For prayer upon the Prophet (peace be upon him) is like other good deeds; it may be accepted or rejected, based on his (peace be upon him) saying: "Whoever performs a deed that is not in accordance with our matter, it is rejected," and his saying: "Indeed, Allah does not accept any deed except that which is done purely for Him and for which His Face is sought." Furthermore, prayer may be rejected if it is tainted by ostentation or innovation, or if the condition of piety is not met, as Allah the Almighty says: "Indeed, Allah only accepts from the righteous."