Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
The merchant in a dream is a man who strives to seek the world. His profit indicates profit in wakefulness, and his loss indicates loss.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
The merchant indicates a striving man (mujahid). He may also indicate a man keen on the world.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
The merchant is interpreted as a striving man. Whoever sees himself as a merchant will gain sustenance and travel.