Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
The river in a dream is a man of high status and importance. Drinking from the river is gaining wealth from a man, proportional to what he drank. Crossing the river is salvation from worry and grief, and victory over an enemy. Clear water in the river indicates the ruler's justice, and murky water indicates his injustice and the corruption of the people.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
The river indicates the ruler. A river flowing in the marketplace indicates the ruler's justice, low prices, and benefit for the public. Entering and exiting the river indicates emerging from worry. Drowning in it indicates strife or worry from the ruler.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
The river is interpreted as a king or a great man. Whoever sees that he owns a river will gain authority and power. Whoever sees the river dry up, the king will die or his authority will cease. Bathing in the river is repentance, purification from sins, and removal of worries.