Kitaab al Eemaan (wa Ma'aalimahu wa Sunanahu wa istikmaalahu wa Darajaatahu).
Translated to: The Book of Eemaan [Faith] (and its Signs, Sunnan, Completion and Levels).
The Imaam Abu 'Ubayd al Qaasim ibn Salaam expounds on the meaning of Eemaan and refutes the sects that have contradicted Ahlus Sunnah and strayed in its Definition and understanding.
He begins by mentioning the reason why he wrote the book; that he was asked about Eemaan and the differing amongst the Ummah concerning it, its completion, increase and decrease as well as the Methodology of Ahlus Sunnah concerning it along with their evidences.
He sectioned the book into eight chapters which are titled, under each chapter he states the relevant Ahaadeeth and Athaar on the topic.
In the first chapter he clarifies the meaning of Eemaan according to Ahlus Sunnah.
In the second he speaks about al Isthithnaa in Eemaan.
The third: The increase and decrease of Eemaan.
In the fourth, fifth and sixth chapters, he refutes the opinions of the sects who contradicted the truth in this matter.
In the seventh and eighth chapters, he speaks about the evidences that negate Eemaan from a person who committed some specific sins.
The author mentions Ahaadeeth with their chain of narration for the most part.
He adds notes, explains and clarifies the correct methodology and refutes those who contradicted it.
Audio Explanations of the Book:
Sharh Kitaab al Eemaan by Shaykh Ibraaheem ar Ruhaylee in eleven parts can be downloaded here.
An explanation by Ummu Salamah al Athariyyah which can be read here.