Book Name:Shaitan kay baaz hathyar
pleasure of Allah عَزَّوَجَلَّ without any involvement of one’s Nafs, desire or worldly benefit in it. (Al-Majmū’ lin-Nawavī, vol. 1, pp. 17)
Meaning of sincerity
Sincerity is the essence of worship. Ṣadr-ush-Sharī’aĥ, Badr-uṭ-Ṭarīqaĥ ‘Allāmaĥ Maulānā Muftī Muhammad Amjad ‘Alī A’ẓamī عَـلَيْهِ رَحْـمَةُ الـلّٰـهِ الۡـقَـوِی has stated, ‘It is vital to perform the deed with sincerity, i.e. with the intention of earning the pleasure of Allah عَزَّوَجَلَّ. It is unanimously Ḥarām to perform the deed ostentatiously. Ostentation [called Riyā in Arabic] is even referred to as minor polytheism in a Ḥadīš. It is sincerity that brings about reward.
It is also possible that the deed becomes invalid but its reward may still be given provided the deed is performed with sincerity. For example, if a person has unknowingly made Wuḍū with unclean water and has offered Ṣalāĥ, though the Ṣalāĥ will not be valid because a precondition, i.e. cleanliness, for the validity of Ṣalāĥ was not met, he will still be given reward because he had offered the Ṣalāĥ with a truthful intention and sincerity. However, if he became aware later on that he had made Wuḍū with unclean water (and his Ṣalāĥ was not valid), he would be required to repeat the Ṣalāĥ. (Baĥār-e-Sharī’at, part 3, pp. 636)