As they moved through the desert, the Israelites were sustained not only by manna and water, but by God’s Spirit (Nehemiah 9:20). As New Testament believers, we should not make the mistake of thinking that God’s blessings to the Israelites were only outward, material blessings. Their blessings, too, were spiritual
(connected to the Spirit).
On two occasions God gave his people water from a rock (Exodus 17:6; Numbers 20:11). Yet Paul seems to be referring not to these two instances, but rather to an oral tradition that existed around the time of the New Testament. According to this tradition, a rock-like source of water followed the Israelites as they journeyed for forty years through the desert.
Whether there was such a rock or not, there was a spiritual Rock
that followed the Israelites, and by which they were nourished. This Rock was Christ.
4 and all drank the same spiritual drink. For they drank from the spiritual Rock that followed them, and the Rock was Christ.