Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
The navel in a dream indicates the mother or the wife. Pain in it indicates worry from them.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
The navel indicates stored wealth. Whoever sees something coming out of it is spending from his wealth.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
The navel is interpreted as a trustworthy servant. Whatever happens to it reflects on him.