وَخَلَّفَ فِيكُمْ مَا خَلَّفَتِ الاْنْبيَاءُ في أُمَمِها، إذْ لَم يَتْرُكُوهُمْ هَمَلاً، بِغَيْر طَريق واضِح، ولاَعَلَمٍ قَائِم "Obedience and a good phrase; but if the affair is determined then should they be true to Allah, it would definitely be superior for them." (Qur'an, 47:21) This guide is translated into various languages http://www.trungtamytechomoi.com.vn/Default.aspx?tabid=120&ch=108123