Sunan ad-Darimi

It is narrated from Abu Raja that in the days of ignorance, if we found a good stone, we would start worshipping it, and if we did not find a good stone, we would gather some sand, then bring a she-camel with plenty of milk, spread her legs wide, and milk her over the heap of sand until it was well soaked. Then, as long as we stayed at that place, we would worship that heap.

Imam Darimi, may Allah have mercy on him, said: «صفي» refers to a she-camel that gives a lot of milk, «فتفاج» means the posture of a she-camel when she spreads her legs to be milked, and for this reason, «فج» refers to a wide road, the plural of which is «فجاج».