Ex 17:6, Deut 8:3, Jn 1:14, Jn 6:32-35,
We usually know that Christ did not work in the Old Testament. No! The Holy Trinity God worked together in both the Old Testament and the New Testament. The Israelites were able to survive in the wilderness with the help of Christ. (1 Cor 10:1-4, Ex 17:6)
1 Cor 10:1 Moreover, brethren, I would not that ye should be ignorant, how that all our fathers were under the cloud, and all passed through the sea; 2 And were all baptized unto Moses in the cloud and in the sea; 3 And did all eat the same spiritual meat; 4 And did all drink the same spiritual drink: for they drank of that spiritual Rock that followed them: and that Rock was Christ.
Ex 17:6 Behold, I will stand before thee there upon the rock in Horeb; and thou shalt smite the rock, and there shall come water out of it, that the people may drink. And Moses did so in the sight of the elders of Israel.
Also, God is teaching the people of Israel that through the difficult life in this wilderness, man can live through Christ, which is found in every word of the Bible. ( Deut 8:3, Jn 1:14, Jn 6:32-35)
Deut 8:3 And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the Lord doth man live.
Jn 1:14 And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
Jn 6:32 Then Jesus said unto them, Verily, verily, I say unto you, Moses gave you not that bread from heaven; but my Father giveth you the true bread from heaven. 33 For the bread of God is he which cometh down from heaven, and giveth life unto the world. 34 Then said they unto him, Lord, evermore give us this bread. 35 And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.