Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
Joy in a dream indicates sadness and worry in wakefulness, especially if it involves noise and dancing. Quiet joy indicates happiness and glad tidings.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
Joy indicates crying and regret. Whoever sees himself happy and joyous will be afflicted with worry proportional to his joy.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
Joy is interpreted as worry and sadness. Joy at another's misfortune indicates gloating and bad character.