Explanation

This Hadīth indicates that whenever anyone greets the Prophet (may Allah's peace and blessings be upon him) Allah returns the Prophet's soul to him so that he greets that person back. Apparently, this applies to those who are close to the Prophet, such that they stand close to his grave and greet him by saying: "May the peace, mercy and blessings of Allah be upon you, O Prophet." It is also possible that it applies in general. Indeed, Allah is over all things Competent.