there is something greater than Jonah here

“At the judgment, the men of Nineveh will arise with this generation and condemn it, because they repented at the preaching of Jonah; and there is something greater than Jonah here.” (MT 12: 41) 

Our Lord wants us to turn to God in genuine repentance because repentance is a change of heart and mind that brings us closer to God. It is putting God in first place; it is following our vocation given by Him and loving Him and others with our whole heart. When we “hear His voice,” we know where to put our hearts. 

“If today you hear his voice, harden not your hearts.