Undoubtedly, the heart leans towards those who are kind and gentle. It was said a long time ago: "Make your face happy and your words gentle, and you will be more beloved to the people than those who give them a gift". The one calling to the religion of Islam and dealing with other people has the utmost need to gather the people around him, and cause their hearts to lean towards him so that they will listen to him. Adorning himself with kindness and gentleness helps to achieve that goal with the grace of Allah.
A short but influential admonition regarding death.
Publisher: Daar Al-Watan
Source: http://www.islamhouse.com/p/1323
Generally regarded as the single most authentic collection of hadiths, Sahih al-Bukhari covers almost all aspects of life in providing proper guidance from the Messenger of Allah. This book is the work of over 16 years by Imam al-Bukhari who before writing any hadith in this book performed two rak'ahs prayer of guidance from Allah and when he was sure of the hadith's authenticity, he wrote it in the book.
Author: Muhammad ibn Ismaeel al-Bukhari
Publisher: http://www.islamspirit.com - Islam Spirit Website
Islam is the religion which Allah has chosen, is pleased with and has legislated for His slaves. People are in dire need of its laws to organize the affairs of their private and public lives, their internal and external affairs. Besides the great importance paid in Islam to general principles and fundamentals, it has not neglected secondary issues.
Author: AbdulRahman Bin Abdulkarim Al-Sheha
Publisher: http://www.islamland.com - Islam Land Website
All in all, this book should provide a good overview towards understanding the many misguided views that emanate from varied groups influenced by the Mu'tazilah.
Author: Sajid Abdul Qayyum
Reveiwers: Muhammad AbdulRaoof
Publisher: A website Quran and Sunnah : http://www.qsep.com
A nice discussion of some important points needed by those callling to Islam
Source: http://www.islamhouse.com/p/1243