What is the legal ruling in Islamic law regarding eating the meat slaughtered by a Muslim or a person of the Book who is uncircumcised, and what is the relied-upon position in the Hanbali school concerning this matter, and does the ruling on the slaughtered meat of an uncircumcised Muslim differ from that of an uncircumcised person of the Book?

Yes, there is a narration from Imam Ahmad that the slaughtered animal of an uncircumcised person (al-aqlaf) should not be eaten. He based this on the statement of Ibn Abbas (may Allah be pleased with him). However, what the madhhab has settled upon is the permissibility of eating the slaughtered animal of an uncircumcised person. This aligns with the view of the majority of scholars and is the more preponderant opinion, because by not undergoing circumcision, he has not exited Islam. Furthermore, the slaughtered animal of a Christian is permissible, even though the majority of them are uncircumcised, and a Muslim has a stronger claim to this permissibility.