He says in the Qur’an:
“…sometimes you may dislike something that is good for you, and
sometimes you may like something that is bad for you. Only Allah
knows the whole truth, not you.” (Quran 2:216)
One of the Awliyah Allah (saint) used to make a Dua (supplication) in
which he said:
“I make Dua to Allah for something I want, and if he gives it to me
then I am happy once, and if he does not give it to me then I am
happy ten times because the first was my choice, but the second was
Allah’s choice.”