Jesus told his disciples:

18 “Hear, then, the parable of the farmer. 19 When anyone hears the word of the Kingdom, and doesn’t understand it, the evil one comes, and snatches away that which has been sown in his heart. This is what was sown by the roadside. 20 What was sown on the rocky places, this is he who hears the word, and immediately with joy receives it; 21 yet he has no root in himself, but endures for a while. When oppression or persecution arises because of the word, immediately he stumbles. 22 What was sown among the thorns, this is he who hears the word, but the cares of this age and the deceitfulness of riches choke the word, and he becomes unfruitful. 23 What was sown on the good ground, this is he who hears the word, and understands it, who most certainly bears fruit, and produces, some one hundred times as much, some sixty, and some thirty.”

Matthew 13:18-23 - World English Bible

In these verses, Jesus explained the meaning of the parable he told publicly in 13:1-8. The farmer was the missionary, spreading the Good News to everyone he met. The soil represent the heart or character of the one who heard the Word. Some people had hard hearts, like the compacted soil of the road, so nothing grew. Some had fickle hearts, like rocky soil, where the Word could not take root; faith was a passing fad and faded away when it met any opposition. Some had hearts with split priorities, so concerned with the cares of the day that faith remained shallow. But, the person who possessed a good heart received the Word and allowed it to grow; this believer became the next missionary, eagerly passing along the Christian message.

Sometimes the question of the heart is not a judgment on others, but phases we go through. What phase in your heart today, hard, rocky, among the thorns or receptive?