Shahdah of oneness of Allah and finality of prophet hood is one of pillars of Islamic belief. If a muslim does not believe that then he is not considered to be a muslim. This book is an effort to explain the meaning of shahdah to all the Spanish speaking muslims or those Spanish speaking people who want to know about Islam. This book is also a great source for dawah.
Other Sources:
Sins and Prohibitions of the Tongue
Softening a hard heart-Bringing attitude of kindness in our lives
How certain Jewish priests hid the birth of Maryam (Mary)?