It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The first Book was revealed through one gate and in one mode, whereas the Qur'an was revealed through seven gates in seven modes, that is, seven categories: restraining, commanding, lawful, unlawful, precise (muhkam), ambiguous (mutashabih), and parables. So treat its lawful as lawful, treat its unlawful as unlawful, act upon what you have been commanded, refrain from what you have been forbidden, take lessons from its parables, act upon its precise verses, believe in its ambiguous verses, and say: 'We believe in it; all of it is from our Lord. And none take heed except those of understanding' [Surah Al Imran: 7] ." This hadith has a sahih (authentic) chain of narration, and the two Shaykhs (Bukhari and Muslim) did not record it.