Assalaamu alaykum. How can a man know if his good works are sincerely for Allaah, The Exalted?

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger. 

You should know that attaining Ikhlaas (devoting one's deeds and intentions sincerely and exclusively to Allah) requires significant striving and such great self-restraint that only a few chosen people can achieve. It is not easy to attain such a refined status, unless Allah, The Exalted, facilities it. Therefore, it is said, “An hour of Ikhlaas is eternal salvation”. Ibn Rajab cited the following statement of Yoosuf ibn Al-Husayn Ar-Raazi : “The most precious thing in this worldly life is Ikhlaas. I strive to remove Riyaa’ (ostentation) from my heart, but it seems to keep coming back in a different form.” [Jaami‘ Al-‘Uloom wa Al-Hikam]

Therefore, claiming that one's deeds are sincerely devoted to Allah is a sign of lack of Ikhlaas. Ibn Al-Qayyim wrote, explaining the definition of Ikhlaas, “A person who considers himself to have attained Ikhlaas should know that his Ikhlaas lacks Ikhlaas. The more the person perceives his Ikhlaas as lacking perfection, the more perfect his Ikhlaas is. When he perceives himself as lacking Ikhlaas, he has genuinely attained it.” [Madaarij As-Saalikeen]

The person may be able to know the extent of his Ikhlaas if he is keen on hiding his good deeds from people; hiding his righteous deeds should be dearer to him than displaying them. Jundub, may Allah be pleased with him, narrated that the Prophet, sallallahu ‘alayhi wa sallam, said, “The one who lets the people hear of his good deeds intentionally to win their praise, Allah will let the people hear his real intention (on the Day of Resurrection), and the one who does good things in public to show off and win the praise of the people, Allah will disclose his real intention (and humiliate him).” [Al-Bukhaari and Muslim]

Imaam Ahmad said about ‘Aasim both, “Abu Waa'il used to sob heavily when praying at home, and if he were to be offered all the treasures of the world to do this before people, he would never accept.” [Az-Zuhd]

One of the signs of a sincere deed that is free of Riyaa' is that the person would not aspire to win people's praise if they knew of his deed. Ibn Al-Qayyim wrote, “As soon as a person attains the rank of humble submission and it takes root in his heart, his spiritual ambition is boosted, and he becomes indifferent to people's praise and dispraise. He would not rejoice at people's praise of him or be saddened by their dispraise. This is the situation of the person who has been freed from the fetters of his self and has been qualified to savor genuine servitude to his Lord, and his heart has tasted the sweetness of faith and certitude.” [Madaarij As-Saalikeen]

For more information, please, refer to fatwa 89311.

Allah knows best.