The Catechism in Questions & Answers

324. What is the significance of the Fourth Commandment in the Old Testament?

Like the Mosaic Law in general, the Fourth Commandment is linked to the desert migration of the Israelites. The people were to provide help and support to older members of their families, and thereby show them honour. The promise of “long days” was understood as wellbeing in earthly life. In Israel, the commandment was also understood as an instruction to adults to take care of those who had grown old and tend to them in the case of illness.

Mosaic Law: see Questions 272. et seq.