Abu Ishaq (may Allah have mercy on him) narrates that Sayyiduna Umar bin Khattab (may Allah be pleased with him) said: Let no one deceive you because he recites the Qur'an; these are merely words uttered by the tongue, but see whether he acts upon it or not.
Hadith Referenceسنن سعید بن منصور / كتاب التفسير / 127