Ephesians 6:2

2.Which is the first commandment with promise. The promises annexed to the commandments are intended to excite our hopes, and to impart a greater cheerfulness to our obedience; and therefore Paul uses this as a kind of seasoning to render the submission, which he enjoins on children, more pleasant and agreeable. He does not merely say, that God has offered a reward to him who obeys his father and mother, but that such an offer is peculiar to this commandment. If each of the commandments had its own promises, there would have been no ground for the commendation bestowed in the present instance. But this is the first commandment, Paul tells us, which God has been pleased, as it were, to seal by a remarkable promise. There is some difficulty here; for the second commandment likewise contains a promise,

“I am the Lord thy God, who shew mercy unto thousands of them that love me, and keep my commandments.”
(Exodus 20:5.)

But this is universal, applying indiscriminately to the whole law, and cannot be said to be annexed to that commandment. Paul’s assertion still holds true, that no other commandment but that which enjoins the obedience due by children to their parents is distinguished by a promise.