A new heart!
The people of Israel have sinned by delving into idolatry. they lost their freedom, their land, their peace, and joy of God's children. The prophet Ezekiel makes a powerful promise according to which, there will soon be a restoration. God will do something new in their lives (Rev 21:5). He will give them a new heart. Jesus fulfilled this promise through his death and resurrection.
That love that springs forth from a pure heart, a good conscience, a sincere faith (1 Timothy 1:5) are indeed the true sign of the wedding garment which God requests from everyone who is freely invited to partake at the eternal banquet.
Immaculate the heart of Mary, pray for us!