Apparently here there are some Jews that are distorting what Paul is teaching. He does not discourage the Jews from obeying the law of Moses. His message is that circumcision and the other customs are not necessary for Jesus to save them. You can make explicit that the leaders of the Jewish believers in Jerusalem knew that Paul was teaching God's true message. (See: [[rc://en/ta/man/translate/figs-explicit]])
This can be stated in active form. Alternate translation: "People have told the Jewish believers" (See: [[rc://en/ta/man/translate/figs-activepassive]])
Here "Moses" stands for the law of Moses. Alternate translation: "to stop obeying the laws that Moses gave us" (See: [[rc://en/ta/man/translate/figs-metonymy]])
To obey the old customs is spoken of as if the customs were leading them and the people were following behind. Alternate translation: "not to obey the old customs" or "not to practice the old customs" (See: [[rc://en/ta/man/translate/figs-metaphor]])