Is it permissible to seek blessing from the person of the Prophet (peace and blessings be upon him), or from his relics, his leftovers, or his grave?

Question : Yes. Although it is not

Answer : This is not shirk (associating partners with Allah), because one seeks blessing through him by the permission of Allah (Mighty and Majestic), and whatever is done by the permission of Allah is not shirk. Even prostration to Adam was shirk, had not Allah commanded it. Yes, seeking blessing from the Messenger (peace and blessings be upon him) during his lifetime is permissible, but after his death, one does not seek blessing from the soil of his grave; rather, one seeks blessing from his relics, just as Umm Salimah used to seek blessing from his hair and use it for healing the sick.