فسـٔل
then pull out (an alif after s is missing to exactly mean "ask", sl means "to unsheathe, draw, pull out")
الذين
those
يقرءون
they are reading (y+ root+wn is progresive or infinitive for they, never past nor past perfect, and to mean "read" has to have an ا
after ر not ء, but any way let say that means read)
الكتب
the books (this word is used in the website of quran corpus as books too)
من
from
قبلك
before you
I don't know how the translators are translating, but I don't see this part of the verse saying go ask the Cristian and the Jews, which will contradict the Quran where God accuses the cristians of following conjectures and the Jews of twisting the words of the book with their tongues and hiding part of it.
What I see Is that is saying "pull out those books from before you that the jews and the cristians are following and see that this is true" because tank Allah the jews and cristians havent corrupted the books as much as they have corrupted themselves, same with millions of muslims who don't follow only the word of allah, even when the quran says that there are not better narratives/histories (haditts) than the narrratives/histories (haddits) of allah, and they have taken their teacher as gidance besides Allah, and use their tasfir, sunnas, haddits to explain the words of the omnipotent, the supreme ruler, the omniscient. They forget that one doesn't need a human teacher to clarify the words of God, HE clarifies His word to whomever he wants of those who have sincerity, humility... He feeds with His wisdom those starving for truth, and guides those who are asking for directions. A human teacher can teach you Arabic or Hebrew or Greek so that you can read the original scriptures, but he will never be able to teach you the wisdom of Allah for He gives it to whomever He wills.