According to the “Seder haDorot” the Children of Israel arrived at Rephidim on the 22rd of Iyar, 2448 (37 days after their exodus from Mitzrayim).
Rephidim was desert land and waterless. G-d commanded Moses to take the elders of the people to a rock which he was to hit with his staff. Moses hit the rock and from the dry stone, a well sprang forth:
“And the haShem said to Moses: pass before the people and take with you [some] of the elders of Israel, and take into your hand your staff, with which you struck the Nile, and go. Behold, I shall stand there before you on the rock in Horeb, and you shall strike the rock, and water will come out of it, and the people will drink. And Moses did so before the eyes of the elders of Israel”. (Shemot, 17:5-6)
According to the “Seder haDorot”, on that day they were given the Miriam’s Well (Be’erah shel Miriam) – the spring that miraculously provided water and accompanied the Israelites throughout the 40 years they traveled in the wilderness.