Isaiah 5:6

I will lay it waste. God did not Himself desolate Israel, but by the withdrawal of His protection, permitted enemies from without, now Assyria and later Babylon and Rome, to accomplish His will (see on 2 Chron. 18:18; 22:8). Later, Isaiah speaks of the Lord’s making use of Assyria as the “rod” of His “anger” and the “staff” of His “indignation” for the punishment of Israel (ch. 10:5-7).

Nor digged. Care is essential if a vineyard is to be productive. Without pruning and cultivation it must eventually deteriorate and become a desolate waste. The cessation of pruning and digging points to the withdrawal of the means of moral and spiritual culture provided by the Lord (Luke 13:8; John 15:2).

Briers and thorns. The once flourishing vineyard would become waste and desolate. Instead of grapes it would produce nothing but briers and thorns. Even the heavens would withhold their blessings, and the land would become parched and barren. It is God who imparts life and blessing (James 1:17). The withholding of His blessings results in desolation and death.