Ibn al-Qayyim said:
Allah, the Exalted, related that His Prophet said to his companion: “Do not grieve; indeed Allah is with us” (At-Tawbah 9:40).
This indicates that there is no grief when Allah is with you, and that whoever has Allah with him what place is there for sadness?
True grief, all grief, is only for the one who misses out on Allah.
So whoever has attained Allah, what is there left for him to be sad about?
And whoever has lost Allah, what is left for him to rejoice over?
Allah, the Most High, said:
“Say: In the bounty of Allah and His mercy — in that let them rejoice.” (Yunus 10:58)