Allah stated that:

(Certainly, the people who were given the Scripture (i.e., Jews and the Christians) know well that, that (your turning towards the direction of the Ka`bah at Makkah in prayers) is the truth from their Lord.)

This Ayah means: The Jews, who did not like that you change your Qiblah from Bayt Al-Maqdis, already knew that Allah will command you (O Muhammad) to face the Ka`bah. The Jews read in their Books their Prophets' description of Allah's Messenger and his Ummah, and that Allah has endowed and honored him with the complete and honorable legislation. Yet, the People of the Book deny these facts because of their envy, disbelief and rebellion. This is why Allah threatened them when He said:

(And Allah is not unaware of what they do.)

(145. And even if you were to bring to the People of the Scripture (Jews and Christians) all the Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.), they would not follow your Qiblah (prayer direction), nor are you going to follow their Qiblah. And they will not follow each other's Qiblah. Verily, if you follow their desires after that which you have received of knowledge (from Allah), then indeed you will be one of the wrongdoers.)