3 occurrences in 3 dictionaries

Reference: Footstool

Easton

connected with a throne (2Ch 9:18). Jehovah symbolically dwelt in the holy place between the cherubim above the ark of the covenant. The ark was his footstool (1Ch 28:2; Ps 99:5; 132:7). And as heaven is God's throne, so the earth is his footstool (Ps 110:1; Isa 66:1; Mt 5:35).

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Hastings

Morish

The usual accompaniment of a throne. 2Ch 9:18. The earth is the footstool of God's throne in the heavens. Isa 66:1; Mt 5:35. It is symbolical of 'the place of rest:' David had it on his heart to build a house of rest for the ark of the covenant of the Lord, and for the 'footstool' of God, wherein God could find rest among His people, and where He was to be worshipped. 1Ch 28:2; Ps 99:5. It is also symbolical of 'subjection to power:' the Lord Jesus must reign until all His enemies are made His footstool. Ps 110:1; Mt 22:44; Ac 2:35; Heb 1:13

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