Be on your guard from a group from the People of the Book

O you who have believed, if you obey a party of those who were given the Scripture, they would turn you back, after your belief, [to being] unbelievers.

[Qur'aan 3:100]

Allaah has warned His believing slaves, in this Noble Verse, to stay on guard against a group from those who were given the Scripture. This group from the People of the Book are those who are jealous of the Muslims because of that which Allaah has given them from His Grace and the blessing conferred upon them by sending His Messenger to them. Allaah says elsewhere in the Qur'aan:

Many of the People of the Scripture wish they could turn you back to disbelief after you have believed, out of envy from themselves [even] after the truth has become clear to them. So pardon and overlook until Allah delivers His command. Indeed, Allah is over all things competent.

[Qur'aan 2:109]

Allaah also exposes the tactics used by some when He says in the Qur'aan:

And a faction of the People of the Scripture say [to each other], "Believe in that which was revealed to the believers at the beginning of the day and reject it at its end that perhaps they will abandon their religion,

[Qur'aan 3:72]