The field is the world. "God so loved the world that He sent His only Son" to give up all that He owned, purchase that field, and die in agony on His cross so the field and its inhabitants might not perish, but have everlasting life (Jn 3:16; Mt 13:44).
The field is full of people. Jesus loves all people, for they are made in His image and likeness (Gn 1:27). To Jesus, this field of humanity is a treasure. He gave all He had to purchase this field (Mt 13:44). Jesus treasures us, and where His treasure lies, there His heart is (Lk 6:45).
Jesus, Emmanuel, God-with-us (Mt 1:23), made His dwelling among us when we were weeds (Jn 1:14). Like a grain of wheat, He fell to the ground and died to bear the fruit (Jn 12:24) of changed lives. He died to change former sinful weeds like us into wheat.
Since Jesus died for us when we were sinners (Rm 5:8), why should we get upset when we have to live in a world full of weed-like sinners? (Mt 13:38) We need not be discouraged. If Jesus treasures sinners so much as to die for them, then as disciples of Jesus, we must do the same. Ask Jesus for His heart, so as to treasure the sinful weeds in our midst. We too must die to ourselves and do whatever it takes, so that at least some might be transformed and saved (see 1 Cor 9:19).
Thank God forever that Jesus loved us when we were sinful and unlovable. Thank God that Jesus treasured us when we weren't so shiny and fruitful. "Go and do the same" (Lk 10:37).