Exodus 23:30

By little and little I will drive them out from before thee, until thou be increased, and inherit the land.

The promise stands within the instruction given to Moses on the mount in Exodus 19-24, written in a book, whose truth and grace Moses was to carry into practice. The divine Teacher who gave those directions on Sinai is Christ Jesus, speaking in human flesh. It belongs to the assurance that God's Angel would lead Israel into the land and that God would cut off its peoples.

God would drive the idolatrous Canaanite inhabitants out little by little, not all at once and not in a single year, until Israel had increased and grown numerous enough to inherit and possess the land. The same gradual driving is taught as the way Israel would increase until able to inherit the land. The delay and gradual process protected the land from becoming desolate while it lacked inhabitants and kept wild beasts from multiplying against the people. That guarding of the land from desolation and from the multiplying of wild animals is the reason given for not driving them out all at once.

The promise of help, reward, and inheritance through that gradual conquest was conditional on obedience to God's commandments. This instruction is needed now just as verily as in the days of Israel, to be studied and presented before the people in jots and tittles as appropriate for the occasion, and believers are to study the commandments and obey them. So studied and obeyed, it ends all contention, humbles hearts to be softened and subdued, leads people to love as brethren, guards against doing injustice, and guides dealings with one another rightly.