John Calvin Commentary Exodus 23:25

"And ye shall serve Jehovah your God, and he will bless thy bread, and thy water; and I will take sickness away from the midst of thee." — Exodus 23:25 (ASV)

And you shall serve the Lord your God. It is true that this promise is very similar to others to which I have assigned a specific place, but it has this difference: that in inviting the people to be zealous in keeping the Law, it sets before their eyes the effect of the covenant already made with their fathers, so that they may more cheerfully receive the Law.

Therefore, there was good reason for my saying just before that the promises which refer to the past have their appropriate place here, where their minds are prepared to obey God and keep His Law. This is because God had chosen the race of Abraham for Himself, that He may continually visit them with His favor.

He therefore promises them His blessing on their bread and water and bodily health, for on these three things depends the condition of our present life. Two other things He adds—fruitfulness in childbearing, and length of days.

The sum is that they had been preceded by God’s loving-kindness, so that they might willingly honor Him, and that now all He had promised them was near, if only they responded to His grace.

But, although the fertility of the land was great, and its produce varied and abundant, no mention is made here, as in other places, of wine or oil, but only of simple food, as if He had said that the necessary supports of life would not be lacking for them.