Ezekiel 37:28
And the heathen shall know that I the LORD do sanctify Israel, when my sanctuary shall be in the midst of them for evermore. And the heathen shall know that I the LORD do sanctify Israel, when my sanctuary shall be in the midst of them for evermore.
The promise is an everlasting covenant of peace in which God places His people and multiplies them, becomes their God while they become His people, sanctifies Israel, and sets His sanctuary in their midst forevermore. When He dwells among His people in His sanctuary, the surrounding nations will recognize that He is the one who sanctifies Israel. That recognition by the heathen is the stated outcome of His abiding presence and sanctifying work.
The verse means deliverance and vindication for those who keep God's commandments. That deliverance belongs to a future time of perplexity and trouble and deception and coming conflict, when commandment-keepers will be challenged.
Their only safety then is unity in the work given them. They must be of one heart, bound up with Christ and with one another and hid with Christ in God. They strengthen themselves by taking hold of His strength and making peace with Him and receiving the experience of Jacob, and then claiming this promise for deliverance, which fills hearts with gladness and lips with joyful praise.