41 Stand therefore firm in your hearts, that no one overthrow you, that no one be able to make you fall. The Apostle has taught us what it is “to stand,” that is what was said to Moses: “The place whereon you stand is holy ground;” for no one stands unless he stand by faith, unless he stands fixed in the determination of his own heart. In another place also we read: “But stand here with Me.” Each sentence was spoken by the Lord to Moses, both “Where you stand is holy ground,” and “Stand here with Me,” that is, you stand with Me, if you stand firm in the Church. For the very place is holy, the very ground is fruitful with sanctity and fertile with harvests of virtues.
Source: Letters (New Advent)