When is a servant's deed accepted, and what are the conditions for a righteous deed to be accepted by Allah?

Work is an act of worship if it combines perfect love and humility before Allah, as stated in the Almighty's words: "But those who believe are stronger in love for Allah" and "Indeed, those who are apprehensive from fear of their Lord." Worship is only accepted from a Muslim monotheist, as stated in the Almighty's words: "And We shall turn to whatever deeds they did, and We shall make them as scattered dust," and in Aisha's narration about Ibn Jud'an. For a Muslim, worship is accepted under two conditions: sincerity of intention for Allah, and conformity to the Sharia, as stated in the Almighty's words: "So whoever would hope for the meeting with his Lord - let him do righteous work and not associate anyone with the worship of his Lord."