Thou preparedst room before it, and didst cause it to take deep root, and it filled the land.

Wesley's Notes

80:9 Preparedst - Thou didst root out the idolatrous nations. Deep root - Thou gavest them a firm settlement.

Matthew Henry's Concise Commentary

80:8-16 The church is represented as a vine and a vineyard. The root of this vine is Christ, the branches are believers. The church is like a vine, needing support, but spreading and fruitful. If a vine do not bring forth fruit, no tree is so worthless. And are not we planted as in a well-cultivated garden, with every means of being fruitful in works of righteousness? But the useless leaves of profession, and the empty boughs of notions and forms, abound far more than real piety. It was wasted and ruined. There was a good reason for this change in God's way toward them. And it is well or ill with us, according as we are under God's smiles or frowns. When we consider the state of the purest part of the visible church, we cannot wonder that it is visited with sharp corrections. They request that God would help the vine. Lord, it is formed by thyself, and for thyself, therefore it may, with humble confidence, be committed to thyself.