Is it true that the Prophet, may God bless him and grant him peace, gave Umar ibn al-Khaṭṭāb, may God be pleased with him, the title Al-Fārūq? And is it permissible for a Muslim to address him by this title out of love for Umar, may God be pleased with him? And what is the ruling on one who objects to that?

The Prophet, peace and blessings be upon him, nicknamed Umar ibn al-Khattab al-Farooq because he distinguished between truth and falsehood. Among the reasons for this nickname is what the commentators mentioned regarding the verse: "Have you not seen those who claim to have believed in what was revealed to you and what was revealed before you? They wish to refer for judgment to Taghut..." [Quran 4:60]. This was when a Jew had a dispute with a hypocrite named Bishr. They referred their case to the Prophet, peace and blessings be upon him, who ruled in favor of the Jew. Then they referred it to Abu Bakr, who ruled similarly to the Prophet's judgment. Then they referred it to Umar. Umar struck the hypocrite with his sword, saying, "This is how I judge one who is not content with the judgment of Allah and His Messenger." So the verse was revealed, and Gabriel said, "Indeed, Umar has distinguished between truth and falsehood." Thus, the Prophet, peace and blessings be upon him, nicknamed him al-Farooq. There is no harm in naming or nicknaming someone al-Farooq, as it is a good title.