Fountain of the sun a spring which formed one of the landmarks on the boundary between Judah and Benjamin (Josh. 15:7; 18:17). It was between the "ascent of Adummim" and the spring of En-rogel, and hence was on the east of Jerusalem and of the Mount of Olives. It is the modern Ain-Haud i.e., the "well of the apostles" about a mile east of Bethany, the only spring on the road to Jericho. The sun shines on it the whole day long.
Dicionário Bíblico Ilustrado de Easton (Easton's Bible Dictionary)
Dicionário Bíblico (Easton)