Exodus Exodus 17:1-7
At Rephidim Israel quarrels and tests YHWH for water, asking 'Is YHWH among us or not?' — and YHWH answers by standing on the rock and having Moses strike it once with the rod that struck the Nile. Paul names the event: 'the rock was Christ' — struck once for all, the source of the living water that becomes the Spirit and the river of life.
Exodus Exodus 16
At the Wilderness of Sin, YHWH rains bread from heaven as a daily test of trust, coins the word 'sabbath' before Sinai, and gives Israel a perishable gift designed to end at Canaan — a downpayment on an imperishable bread and an imperishable rest.