On

On, also known as Heliopolis (Greek for "City of the Sun"), was an ancient Egyptian city located in the Nile Delta region, near modern-day Cairo. It is mentioned several times in the Bible, particularly in relation to the life of Joseph. Joseph married Asenath, the daughter of Potiphera, a priest of On (Gen. 41:45, 50; 46:20). This marriage was arranged by Pharaoh and likely served to integrate Joseph into Egyptian society and religious life.

The city of On was a center of worship for the sun god Ra and was known for its temples and religious institutions. In the prophetic books, On is mentioned in the context of God's judgment against Egypt (Ezek. 30:17). Some translations and ancient versions (such as the Septuagint) also reference On in Isaiah 19:18, where it is called the "City of Destruction" or "City of the Sun," depending on the interpretation of the Hebrew text.