Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
The dragon in a dream is a tyrannical king, a great enemy, or a raging sea. Whoever sees himself riding a dragon will gain a great kingdom or travel by sea on a dangerous journey. Killing it indicates victory over a strong enemy.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
The dragon indicates an unjust ruler, fire, or heresy. Whoever turns into a dragon will have a long life and gain authority. Eating its meat indicates gaining wealth from the king.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
The dragon is interpreted as the sea, the king, or a man of great danger. Riding it indicates gaining a great kingdom, proportional to its obedience. Whoever sees himself fighting a dragon is fighting a tyrannical king.