Tafsir of Al-Insan 76:18

A spring there, called Salsabil. Ikrimah said, "It (Salsabil) is the name of a spring in Paradise.'' Mujahid said, "It is called this due to its continuous flowing and the severity of its current.'' The Boys and Servants Allah says,

ويطوف عليهم ولدان مخلدون إذا رأيتهم حسبتهم لولوا منثورا