Mishkat al-Masabih 186
Malik b. Anas, in mursal form, reported God’s messenger as saying, “As long as you hold fast to two things which I have left among you, you will not go astray:
God’s Book and His messenger’s sunna ” 

He transmitted it in Al-Muwatta .
وَعَن مَالك بن أنس مُرْسَلًا قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: " تَرَكْتُ فِيكُمْ أَمْرَيْنِ لَنْ تَضِلُّوا مَا تَمَسَّكْتُمْ بِهِمَا: كِتَابَ اللَّهِ وَسُنَّةَ رَسُولِهِ «. رَوَاهُ فِي الْمُوَطَّأ»