Sincerity of Determination and Deeds
There is nothing more useful to the servant of Allah then being sincere with his Lord in all matters, especially sincerity for determination. The servant should be sincere in both his determination and in his deeds. Allah Subhanahu wa Ta’ala says which means:
“And when the matter (preparation for Jihad) is resolved on, then if they had been true to Allah, it would have been better for them." (Surah Muhammad 47: 21)
He will find happiness by being sincere in both determination and the truth of his deeds. Sincerity of determination is achieved through resolving and removing any hesitation. If he is sincere in his determination, the truth of his deeds still remains to be fulfilled, which is dedicating one’s power and efforts without losing anything from either the inner or the outer. Determination prevents weakness of will and intention, and truthful deed prevents him from laziness and apathy.
And whoever is true to Allah in all matters, Allah will grant him more than He does with others. This truth is a means that results from combining true sincerity and pure trust. The most truthful among people are those who are granted these characteristics.
Reference: Al-Fawaid – Ibn Al-Qayyim (Rahimahullah) Page310