Matthew 10:40 "Whoever receives you receives me, and whoever receives me receives him who sent me. 41 The one who receives a prophet because he is a prophet will receive a prophet's reward, and the one who receives a righteous person because he is a righteous person will receive a righteous person's reward. 42 And whoever gives one of these little ones even a cup of cold water because he is a disciple, truly, I say to you, he will by no means lose his reward."
Understanding the meaning of "receive" gives clarity to what Jesus is saying in verses 40 and 41. Receive means "to accept the word or teaching indicating approval or conviction of what is said." The three following scripture clarify the meaning of "receive" as used by Jesus in our passage before us today.
1 Thessalonians 1:6 And you became imitators of us and of the Lord, for you received the word in much affliction, with the joy of the Holy Spirit.
Hebrews 11:31 By faith Rahab the prostitute did not perish with those who were disobedient, because she welcomed the spies in peace. ("welcomed" is same Greek word translated "received" in the above verse)
James 1:21 Therefore put away all filthiness and rampant wickedness and receive with meekness the implanted word, which is able to save your souls. (the implanted word is the word someone has taught us or implanted in us
In each of the above verses the people received the message brought by people who came to them and thus received them.
Jesus is saying to us that if we receive the message of the person sent by Him, we receive Him and thus receive His Father who sent Him. If we receive the message of the prophet and the righteous man as our own conviction, then we will receive the same reward as they receive. Example: If I go to my neighbor with the gospel message in obedience to the Lord and my neighbor receives me and by receiving me receives the gospel message, then my neighbor will receive the reward of eternal life just as I have.
In verse 42 Jesus instructs us that we will not lose our reward if we help a little one who a disciple of Jesus. Jesus places high value on children by saying this. Remember that the disciples had tried to prevent the children from coming to Him (Matthew 19:13-14).
It is important that we receive those Jesus sends to us to instruct us. It is important that we help all disciples and not just those we think are worthy to come to Jesus, but those who have come to Jesus.