Tafsir of Al-Ma'idah 5:81

(And if they had) — that is, those who take the polytheists as allies — (believed in Allah and the Prophet) — meaning their prophet, Moses, peace be upon him, (and what was revealed to him) — meaning the Torah. It is also said that the intended meaning of "the Prophet" is our Prophet Muhammad, may Allah bless him and grant him peace, and by "what was revealed to him," the Quran. This means: If the hypocrites had believed in Allah the Exalted and our Prophet Muhammad, may Allah bless him and grant him peace, with a true belief, (they would not have taken them) — meaning the polytheists or the openly hostile Jews — (as allies). For the aforementioned belief is definitively a deterrent against taking them as allies. (But many of them are defiantly disobedient) — meaning they have exited the religion, or they are rebellious in their hypocrisy, exceeding all bounds in it.