3:78

There are some among them who twist their tongues pretending a quote from their Holy Book; so that you may think that what they read is a part of the Book, whereas, in fact it is not a part of the Book. They also assert, “It is from Allah” whereas, in fact it is not from Allah. Thus they deliberately ascribe a lie to Allah.
Meaning:-
Assert: argue, proclaim, swear, insist, declare.
Deliberately: intentionally, purposely, knowingly, consciously.
Ascribe: to attribute or think of as belonging, as to a cause or source;