In the bible, Rahab the prostitute helped the two spies sent by Joshua and when the time was right, both she and her family were spared from the calamity that befell the city of Jericho. No matter the situation we are, there is always someone out there that needs our help, and this should be reciprocated.
David was helped by Abigail when he was hungry, and her husband Nabal had insulted him and refused to help him. David repaid her by marrying her after the death of her husband Nabal. Even when he was about to die, he told his son Solomon to repay the sons of Barzillai of Gilead, who had helped him when he fled from Absalom his son. He also helped Mephibosheth, Jonathan's son because of what his friend Jonathan had done for him when he was alive. He gave him Saul's inheritance, permitted him to live in the palace at Jerusalem and allowed him to eat at his table.
Proverbs 3:17 says that if you repay good with evil, evil will never leave your house.
Always strive hard to repay good with good. By doing this, God will bless you and good will never leave your house. It is a way to thank the person who have helped you and this can make the person help you again when you ask for help.