What does Matthew 10:3 mean?

Matthew is listing the Twelve: Jesus' hand-picked group of apostles. The term "apostle" comes from a Greek word meaning someone who is sent out, on behalf of their master, with a certain message or mission. Jesus has given these men His authority to go to the towns and cities of Israel. They are to preach the gospel of the kingdom of heaven while also casting out demons and healing the sick (Matthew 10:1).

Matthew is listing them in pairs of two, perhaps as they were teamed up and sent out by Jesus after His instructions to them were completed. Matthew has already listed the two pairs of brothers: Peter and Andrew, as well as James and John, all fishermen before following Jesus.

Now he lists Philip and Bartholomew. Like Peter and Andrew, Philip was from the town of Bethsaida. Commentators think Bartholomew may also have been known as Nathanael, since Philip is the one who brought Nathanael to meet Jesus and they are listed here together (John 1:44–51). Many people in this era used more than one name.

Matthew next lists himself, along with Thomas. Thomas was also called "Didymus," which means "twin" (John 11:16). He famously became known as "doubting Thomas" because he refused to believe without evidence that Jesus had been resurrected (John 20:24–29). Matthew, in apparent humility, describes himself as the "tax collector" (Matthew 9:9), something Mark and Luke do not mention in their lists.

Little is known about James, the son of Alphaeus. He is only mentioned in the lists of apostles. The James who wrote an epistle included in the New Testament (James 1:1; Galatians 2:9) is a different person. Thaddaeus was likely also known as Judas, the son of James, the name listed in Luke 6:16 and Acts 1:13 instead of Thaddaeus. He is not Judas Iscariot, who will betray Jesus. The betraying Judas is always mentioned last in the lists of the disciples.