Hadith is the second fundamental source of Islamic law. They are the words, actions, and sanctions of the Holy Prophet. To record all these in memory and writing, to compile it and to record the biography of those narrators who did this great job, and this is considered as a miracle of the Prophet. But the enemies of Islam used to create doubts in this regard. This book is written on this subject, and it is enough an answer to all the objections that people made from different angles.