29) to walk in God's law, and to observe and do all the commandments.

What need after that to enter a single other article in the covenant?
If a man walks in God's law he cannot go wrong; if he keeps all God's commandments, what more can be required?
But they were wise men who drew up that solemn covenant.

They knew and understood the human heart.

Is it not a fact, that whilst we are all ready to own that we are sinners in a general sense, we are slow to own that we are guilty of any particular sin?
We do not mind confessing that we are miserable sinners, but we should indignantly deny being selfish or idle, or unforgiving, or proud, or bad-tempered.
So those who wrote the parchment felt it best to go more into detail, and to put down certain things in which they felt they had done wrong in the past, but in which they meant to do better in the time to come.
(1) They promised that they would not in future marry heathen people, that they would not give their daughters to heathen men, or let their sons choose heathen wives.
(2) They engaged to keep the Sabbath, and not to buy and sell on the holy day; and they promised that if the heathen people round came to the city gates with baskets of fruit, or vegetables, or fish on the Sabbath, they would refuse to buy.
(3) They stated that for the future they would keep every seventh year as a year of Sabbath.

The Sabbath year had in times past been a great blessing to the land.