Study Notes on Soorah al Kahf verse 22

Verse 22. Some people will say that they were three, the dog being the fourth; others wil say they were five, the dog being the sixth. These are mere irrelevant guesses; there are still others who say they were seven, their dog being the eight. Say: “My lord knows their number and only a few others besides Him know.” So do not argue about them, except with clear proof. Nor ask anyone about them.

Allah confirms that their number was seven because after saying that they were three and five He goes on to say that these are mere guesses, but after mentioning the number seven He did not say that it was false which implies that this was the actual number.

Ibn Abbas “I am among the few who know the right number and they were seven.” (Tafsir Ibn Kathir).

We should only discuss concerning the People of the Cave using what has been revealed or avoid arguing concerning the exact number which has no benefit.
Arguments should only be superficial; if the argument reaches the heart, he will become more argumentative, angry and his ego inflated and he will be affected. Scholars of Kalam's unnecessary rules and statements like “an infinite chain of incidents into the past and future” have volumes of writing affirming or negating this issue.

Concerning Taking from books of Jews and Christians for Da'wah purposes.

Hadeeth the prohibits: Umar wanting to read some sayings from the Torah...“By the One in whose Hand my soul lies! If Moses were to appear among you and you followed him and abandoned me, you would have gone astray. You are my portion of the nations and I am your portion of the prophets.” (Musnad Ahmad

Hadeeth that permits: The hadeeth concerning Jewish man and woman committing adultery and the verse of stoning in the Torah where a Rabi hid a verse by placing his hands over it. The prophet ordered them both to be stoned to death. (Bukhari).

Quranic Verses that permits: “Those who follow the Messenger, th Prophet who can neither read nor write whom they find written with them in the Torah (Deuteronomy 18:15) and the Gospel (John 14:16)” (7:156). See also (61:6).

Another Hadeeth that Permits: “Convey whatever you have learned from me, even if it is only a single verse. And you may speak about the People of Israel without any fear of sin.”(Bukhari).

RECONCILING THE APPARENT CONTRADICTION

Ibn Hajar al Asqalani: means there are no constraints in speaking about them.
Abrogation; previously discouraged then allowance was made. The prohibition occurred prior to the stabilization of Islamic laws and religious principles, for fear of confusion.

Ash Shafi'ee: It is known that the Prophet did not permit speaking lies. So, the meaning of “Speak about the People of Israel without fear of sin,” is that you may speak about them concerning what you do not know to be lies.

Commentator of Sunan at Tirmidhee: the conflict may be resolved by understanding that the intention of the prohibition here was the prohibition against taking laws from their scriptures, because all legal systems and religions were abrogated by our Prophet's legal system.