Ibn ‘Umar (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "If a slave is sincere to his master and worships Allah well, He will have a double reward." Abu Mūsa al-Ash‘ari (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "A slave who worships his Lord well and fulfills his responsibilities to his master, being sincere and obedient to him, will have a double reward."
عن ابن عمر-رضي الله عنهما- مرفوعاً: «إن العبد إذا نصح لسيده، وأحسن عبادة الله، فله أجره مرتين». عن أبي موسى الأشعري -رضي الله عنه- مرفوعاً: «المملوك الذي يحسن عبادة ربه، ويُؤدي إلى سيده الذي عليه من الحق، والنصيحة، والطاعة، له أجران».
شرح الحديث :
This Hadīth mentions the blessings that Allah bestows upon a servant who fulfills Allah's rights upon him by performing acts of obedience to Allah and at the same time he fulfills the rights of his master by serving him and taking care of his needs. If the servant does this he will receive a double reward.