Shaykh al-‘Uthaymeen gives us a concise work, affordable and educational, as usual, on the Science of Hadeeth.
This is a summary of the science and rules of hadith, the book is known and recommended.
The Prophet SAW said: “Indeed, actions are but by intentions and every person shall have but that which he intended. Thus, he whose Hijrah (migration) was for Allah and His Messenger, his migration was for Allah and His Messenger. And he whose migration was to achieve some worldly benefits or to take some woman in mirage, his migration was for that for which he migrated.”