Haram bin Mu'awiyah (may Allah have mercy on him) says that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) wrote: "Train the horses, but let the cross not be raised among you, nor let pigs live near you."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18713
Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says: In every city that the Muslims have founded, the Jews and Christians shall not build their places of worship, nor shall the clapper-bell (naqus) be struck, nor shall pork be sold.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18714