Matthew 10:42 - And if anyone gives even a cup of cold water to one of these little ones because he is my disciple, I tell you the truth, he will certainly not lose his reward.
When Jesus walked on earth He had a lot of followers, but only twelve that He called His disciples. These twelve lived with Jesus. They were with Him all the time: morning. noon and night. Jesus taught them and they patterned their lives after His words. All in all, they wanted to be like Jesus.
When Jesus returned to heaven He sent the Holy Spirit to earth to come into the hearts and lives of those who Love Him. Through the Holy Spirit we all can become disciples of Jesus. We are able to live with Jesus as well. He is with us everyday; all the time, and we have the option of patterning our life after Him.
As we live our life like Jesus did we see that He walked in Love and compassion. First of all His Love for God was unparalleled, but there was also His Love for people. When He saw people hurting or lost He could not simply walk by. Jesus would stop and help them.
Even now, as Jesus is in us, it pains Him when we ignore those who need help. That is why Jesus makes this statement. He says if you are His disciple and give even a cup of cold water to a little one you will be rewarded.
That is Jesus heart and desire: to see us help those in need and Love those who are unloved. A cup of water may seem trivial in the overall scheme of things, but it definitely makes a difference to the one you gave it too. That child will remember it forever.
If you call yourself a disciple then you ought to walk as Jesus walked. Show Love to those around you.