And the Lord said - i. e. answered by Urim and Thummim. The land was the portion which fell to Judah by lot, not the whole land of Canaan (see Judges 3:11). The priority given to Judah is a plain indication of divine direction. It points to the birth of our Lord of the tribe of Judah. Judah associated Simeon with him Judges 1:3 because their lots were intermingled Joshua 19:1.

The Lord said, Judah shall go up - They had inquired of the Lord by Phinehas the high priest; and he had communicated to them the Divine counsel.

And the Lord said,.... By an articulate voice, which it is probable was the usual way of answering by Urim and Thummim:
Judah shall go up; not Judah in person, who was long ago dead, but the tribe of Judah; it was the will of the Lord that that tribe should engage first with the Canaanites, being the principal one, and the most numerous, powerful, and valiant, and perhaps had the greatest number of Canaanites among them; and who succeeding, would inspire the other tribes with courage, and fill their enemies with a panic:
behold, I have delivered the land into his hands; that part of it which belonged to that tribe as yet unsubdued, the conquest of which they are assured of for their encouragement.

the Lord said, Judah shall go up--The predicted pre-eminence (Genesis 49:8) was thus conferred upon Judah by divine direction, and its appointment to take the lead in the ensuing hostilities was of great importance, as the measure of success by which its arms were crowned, would animate the other tribes to make similar attempts against the Canaanites within their respective territories.
I have delivered the land into his hand--not the whole country, but the district assigned for his inheritance.

Judah - The tribe of Judah is chosen for the first enterprise, because they were both most populous, and so most needing enlargement; and withal most valiant, and therefore most likely to succeed: for God chooseth fit means for the work which he designs. Moreover the Canaanites were numerous and strong in those parts, and therefore to be suppressed, before they grew too strong for them.