Deuteronomy 25:15
You must maintain accurate and honest weights and measures, so that you may live long in the land that the LORD your God is giving you.
What it says
Weights and measures must be accurate and honest, so Israel may live long in the land the Lord gives.
What it is doing
It joins commercial honesty to covenant blessing in the land.
In context
13You shall not have two differing weights in your bag, one heavy and one light. 14You shall not have two differing measures in your house, one large and one small. 15You must maintain accurate and honest weights and measures, so that you may live long in the land that the LORD your God is giving you. 16For everyone who behaves dishonestly in regard to these things is detestable to the LORD your God.