Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
The donkey indicates luck, fortune, and fate. Riding it is gaining adornment and status. Its death is the death of its master or the loss of his wealth. Its braying is ugly speech from a foolish man.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
The donkey indicates a son, travel, or a scholar without action. A fat donkey indicates the dreamer's wealth, and a thin one his poverty. The donkey carrying the dreamer indicates the strength of his luck.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
The donkey is interpreted as luck. A white donkey is good luck, a black one is leadership and wealth, and a green one indicates a pious, god-fearing man.