איבער אַ גלייַך צווייפל

That captures the core theological explanation found in both the Old and New Testaments.

Scripture explicitly contrasts the external law written on stone tablets at Mount Sinai with an internal transformation. Because the people repeatedly broke the external Mosaic covenant, the prophetic promise focused on changing the human heart so obedience would come from within rather than from outward compulsion.

A few key passages directly emphasize that contrast:

Ezekiel 36:26–27: "I will give you a new heart and put a new spirit within you; I will take the heart of stone out of your flesh and give you a heart of flesh. I will put My Spirit within you and cause you to walk in My statutes, and you will keep My judgments and do them."

2 Corinthians 3:3: The Apostle Paul highlights this exact shift, describing believers as "an epistle of Christ... written not with ink but by the Spirit of the living God, not on tablets of stone but on tablets of flesh, that is, of the heart."

Hebrews 8:7–8: Explains that "if that first covenant had been faultless, then no place would have been sought for a second," noting that the flaw lay in the people's failure to keep it: "Because finding fault with them, He says: 'Behold, the days are coming... when I will make a new covenant.'"

In biblical theology, the shift from stone to the heart represents moving from an external standard that condemned failure to an internal grace and renewal that empowers people from the inside out.

"Behold, the days are coming, says the Lord, when I will make a new covenant with the house of Israel and with the house of Judah—not according to the covenant that I made with their fathers in the day that I took them by the hand to lead them out of the land of Egypt, My covenant which they broke, though I was a husband to them, says the Lord. But this is the covenant that I will make with the house of Israel after those days, says the Lord: I will put My law in their minds, and write it on their hearts; and I will be their God, and they shall be My people."

— Jeremiah 31:31–33 (NKJV)

The passage is also quoted in the New Testament in Hebrews 8:8–10.