Commentaries:
A person who has properly obeyed his parents in childhood later expresses his honor for them in a deeper appreciation of the comforts and training they provided him as a child. This honor expresses itself in courtesy, thoughtfulness, and kind deeds. Any parent, especially a widowed parent, should be repaid by his children for the care given them as they grew up. Even in His dying moments, while suffering an agonizing death, Jesus honored and loved His mother by making provision for John to care for her after His death (John 19:26-28). God our Father is well pleased with us when we obey this vital commandment (Colossians 3:20).
Martin G. Collins
The Fifth Commandment
What Paul says here often presents great difficulties under modern conditions, especially when young people must choose between caring for parents and furthering their ambitions or establishing a home. Paul teaches that not only children but also grandchildren have a definite obligation to live their religion by providing for their needy parents or grandparents. He bluntly states that they are to repay them for all their kindness and sacrifices. A child can never wholly repay this debt, but still he should consider it a sacred obligation to make it up as much as possible.
John W. Ritenbaugh
The Fifth Commandment (1997)