Here are 8 Bible verses about courtesy from the Old and New Testaments of the Holy Bible (King James Version), sorted from most to least relevant.
Romans 15:1-5 KJV
We then that are strong ought to bear the infirmities of the weak, and not to please ourselves. Let every one of us please his neighbour for his good to edification. For even Christ pleased not himself; but, as it is written, The reproaches of them that reproached thee fell on me. For whatsoever things were written aforetime were written for our learning, that we through patience and comfort of the scriptures might have hope. Now the God of patience and consolation grant you to be likeminded one toward another according to Christ Jesus:
1 Thessalonians 5:15 KJV
See that none render evil for evil unto any man; but ever follow that which is good, both among yourselves, and to all men.
1 Peter 3:8 KJV
Finally, be ye all of one mind, having compassion one of another, love as brethren, be pitiful, be courteous:
Colossians 4:6 KJV
Let your speech be alway with grace, seasoned with salt, that ye may know how ye ought to answer every man.
Acts 27:3 KJV
And the next day we touched at Sidon. And Julius courteously entreated Paul, and gave him liberty to go unto his friends to refresh himself.
Luke 6:35 KJV
But love ye your enemies, and do good, and lend, hoping for nothing again; and your reward shall be great, and ye shall be the children of the Highest: for he is kind unto the unthankful and to the evil.
Acts 28:7 KJV
In the same quarters were possessions of the chief man of the island, whose name was Publius; who received us, and lodged us three days courteously.
Ruth 2:14-18 KJV
And Boaz said unto her, At mealtime come thou hither, and eat of the bread, and dip thy morsel in the vinegar. And she sat beside the reapers: and he reached her parched corn, and she did eat, and was sufficed, and left. And when she was risen up to glean, Boaz commanded his young men, saying, Let her glean even among the sheaves, and reproach her not: And let fall also some of the handfuls of purpose for her, and leave them, that she may glean them, and rebuke her not. So she gleaned in the field until even, and beat out that she had gleaned: and it was about an ephah of barley. And she took it up, and went into the city: and her mother in law saw what she had gleaned: and she brought forth, and gave to her that she had reserved after she was sufficed.