A slave stands infront of Allah on two occasions. The first during salah, and secondly on the Day of Judgment. Whoseover stands correctly in the first, the second standing will be made easier for him. And whosoever, disregards the first standing, the second standing will be extremely difficult.
Ibn Qayyim Al-JawziyyaThe ibtilaa' (testing) of the believer is like medicine for him. It cures him from illness. Had the illness remained it would destroy him or diminish his reward and level (in the hereafter). The tests and the trials extract these illnesses from him and prepare him for the perfect reward and the highest of degrees (in the life to come).
Ibn Qayyim Al-JawziyyaWhoever mocks his brother for a sin they repented from will not die till he himself falls into the same sin.
Ibn Qayyim Al-JawziyyaAnd verily for everything that a slave loses there is a substitute, but the one who loses Allah will never find anything to replace Him.
Ibn Qayyim Al-Jawziyya