Abstract: In Islam, ethics (akhlaq) is inseparable from religion and is built entirely upon it. Naturally therefore, the Quran and the Sunnah are the ultimate sources for Muslim ethics. The books on adab (good manners) and makarim al-akhlaq (noble qualities of character) which have embodied the earliest works on ethics in Islam demonstrate, the extent to which they utilize the Quran and the Sunnah. However, early Muslim discussions on ethics, such as those by Al-Kindi (d.874), Al-Farabi (d.950) and Ibn Sina (d.1037) did not attain to the status of a discipline though invariably serving as an introduction to their wider studies on politics, law and other fields of knowledge. Miskawayh (d.1030), Al-Ghazali (d.1111), Al-Tusi (d.1274) and Al-Dawwani (d.1502) through their major respective research on ethics, Tahdhib Al-Akhlaq, Ihya’ ‘Ulum al-Din, Akhlaq Al-Nasiri and Akhlaq Al-Jalali have separated ethics from other disciplines, offering a very thorough analytical system of Islamic ethics. Thus, this qualitative study which applies conceptual content analysis method seeks to make a critical study of the meaning and development of ethical thought in Islam.