"Beloved, you are acting faithfully in whatever you accomplish for the brethren, and especially when they are strangers; and they
have testified to your love before the church."
(3 John 1:5-6)
Christian travelers in John's day depended upon the hospitality of other Christians. Extending hospitality is not a small thing to God. It is a fulfillment of God's command to "love on another". Even a cup of cold water offered to one of God's children will not be forgotten by God. (Matthew 10:42). John praises Gaius, who is well-known for his hospitality; those who have received his hospitality have testified to it. "What high praise: you do faithfully whatever you do! Whatever God has given us to do, we should do faithfully. Jesus said that when we see Him face to face, some would hear the words, well done, good and faithful servant; you were faithful over a few things, I will make you ruler over many things. Enter into the joy of your lord. (Matthew 25:21) Of the good servant, it is said he was faithful." (David Guzik)