Some versions have, stretch, or, establish.

Referring here to the redemption of God’s people for their release from captivity in Babylon, after which they could return (cf. Exo. 6:6). Before God could redeem His people from captivity, they had to be redeemed from sin under God’s condemnation, as illustrated by the redemption through the passover lamb prior to the exodus from Egypt (Exo. 12).

Signifying the strength of Jehovah, the dynamic might of Christ in His divinity, and referring to Christ as the all-inclusive Servant of Jehovah (Isa. 53:1-2) in relation to Israel’s return from captivity (Isa. 52:10-12). In Israel’s return and restoration, the all-inclusive Christ is, first, the arm of Jehovah, second, the reigning God (52:7), and, third, the exalted Christ (Isa. 52:13).

Referring not to God but to Abraham, who was the source of Israel. Jehovah’s calling of Israel is based on His calling of their father Abraham; hence, it is firm.