King James Version
Wherefore it shall come to pass, if ye hearken to these judgments, and keep, and do them, that the LORD thy God shall keep unto thee the covenant and the mercy which he sware unto thy fathers:English Standard Version
"And because you listen to these rules and keep and do them, the LORD your God will keep with you the covenant and the steadfast love that he swore to your fathers.New International Version
If you pay attention to these laws and are careful to follow them, then the LORD your God will keep his covenant of love with you, as he swore to your forefathers.