Rejoicing (merriment) فرح

In a dream, if it is over something that does not please the heart, it signifies worry and sorrow, because of His saying, the Exalted:

۞ إِنَّ قَـٰرُونَ كَانَ مِن قَوْمِ مُوسَىٰ فَبَغَىٰ عَلَيْهِمْ ۖ وَءَاتَيْنَـٰهُ مِنَ ٱلْكُنُوزِ مَآ إِنَّ مَفَاتِحَهُۥ لَتَنُوٓأُ بِٱلْعُصْبَةِ أُو۟لِى ٱلْقُوَّةِ إِذْ قَالَ لَهُۥ قَوْمُهُۥ لَا تَفْرَحْ ۖ إِنَّ ٱللَّهَ لَا يُحِبُّ ٱلْفَرِحِينَ

“Indeed, Qārūn was from the people of Moses, but he tyrannized them. And We gave him of treasures whose keys would burden a band of strong men; thereupon his people said to him, "Do not exult. Indeed, Allāh does not like the exultant.”

Quran 28:76 · Saheeh International

It may signify being distracted from obedience to God. If the rejoicing is over good news, such as the release of a prisoner or the recovery of a sick person, these are good transitions and causes of joy. If in the dream he is told something that calls for joy but is in reality sad, like someone told in a dream that so-and-so has returned from his journey when he has in fact passed away in death, it signifies trouble giving way, from a loss to a profit or from a profit to a loss. Rejoicing in a dream is worry: whoever sees that he rejoiced will be grieved.