One of the Least of These Commandments
While the fulfillment of Mt. 5:17-18 emphasizes all the events the law and prophets prophesied would come to pass before heaven and earth pass away, the fulfillment of the law and prophets will also include commands. In Mt. 5:19 Jesus refers to the least of these commands. Most interpreters think of 5:18 and the smallest letters or marks of the law of Moses. But 5:18 is about what events, not what laws, will come to pass, will happen, in the future.
So what commands is Jesus talking about? Has he given any commands yet? Yes indeed, in the verse immediately before 5:17, Jesus commands his disciples to let their light shine before men (5:16). This command will fulfill their being the light of the world (5:14). And this expanded vision of the world beyond Israel, his new international kingdom, is what leads to his words in 5:17-19 about how he comes to fulfill, not destroy, the law and the prophets of the kingdom of Israel.
In 4:14-16 Jesus says he is fulfilling the prophet Isaiah by being the great light that Galilee of the Gentiles now sees. This is reinforced later in Mt. 12:17-21, where Jesus again says he is fulfilling the prophet Isaiah by proclaiming justice (righteousness) to the Gentiles, who will find hope in him. So Jesus’ fulfillment means a new world mission, and a new worldwide kingdom. This is the basis for his new command in 5:16.
This command could also be (dis)regarded as the least of his commands by Jewish disciples who have grown up hating Gentiles. When a scribe (teacher) of the Pharisees later asks Jesus what is the great command in the law, Jesus quotes Deut. 6:5 (love God with all your heart, soul, and mind) and Lev. 19:18 (love your neighbor as yourself). When Jesus refers to this (second) great command in Mt. 5:43, he adds another (former command): “and hate your enemies.”
The main enemies the law (of Moses) says to avoid, or to destroy, are the Gentiles, especially those living in the promised land (for example, Lev. 20:23-24; 26:6-8). Lev. 19:18 defines the neighbor (in “love your neighbor”) as “the sons of your own people.” So early on, in Jesus’ new kingdom, Jewish disciples have trouble reconciling his new commands about reaching out to Gentiles, to the world, and their traditions and laws about hating Gentiles.
Some Jewish disciples might (and will) decide that this command about being light to the world is the least of their concerns. Jesus warns such disciples: they will be called least in the kingdom of heaven (5:19). Only disciples who do and teach such difficult commands will be called great in the kingdom of heaven.
Shortly, in 5:21-48, Jesus will give more new commands; these will also fulfill–“fill out” and sometimes replace–several of the most basic commands of Moses. Jesus’ disciples must take all these new commands seriously if they are to receive their reward in the end. Disciples who do and teach even the least of these commands will be called great in the kingdom of heaven (5:19). Jesus is talking about his commands and rewards in the kingdom of heaven, not the commands and rewards of Moses in the kingdom of Israel.