Yes, this is an authentically narrated hadith found in Sahih Muslim, one of the two most rigorously verified hadith collections (alongside Sahih al-Bukhari). The Prophet Muhammad (peace be upon him) stated clearly that Abdullah (‘servant of Allah’) and Abdur-Rahman (‘servant of the Most Merciful’) are the most beloved names to Allah. Scholars explain this is because both names directly and unambiguously express ‘ubudiyyah — servitude and submission to Allah alone — which is the core message of Islam. This is why these two names remain among the most widely used Muslim boy names across the world to this day.