But if any widow have children - Who would be dependent on her care, and who might themselves contribute to her support.
Or nephews - The word nephew now commonly means the son of a brother or sister. Formerly the English word also meant grandchildren, or descendants of any description. Webster. The Greek word here - ἔκγονα ekgona - has the latter meaning. It denotes those “sprung from or born of;” and then descendants of any kind - sons, daughters, grandchildren. The Greek word would not, in fact, properly include nephews and nieces. It embraces only those in a direct line.
Let them learn first to show piety at home - Margin, “or kindness.” That is, let the children and grandchildren learn to do this. Let them have an opportunity of performing their duty toward their aged parent or grandparent. Do not receive such a widow among the poor and dependent females of the church, to be maintained at public expense, but let her children support her. Thus they will have an opportunity of evincing Christian kindness, and of requiting her for her care. This the apostle calls “showing piety” - εὐσεβεῖν eusebein - that is, “filial piety;” piety toward a parent by providing for the needs of that parent in advanced age. The word is commonly used to denote piety toward God, but it is also used to denote proper reverence and respect for a parent. Robinson.
And to requite their parents - To repay them, as far as possible, for all their kindness. This debt can never be wholly repaid, but still a child should feel it a matter of sacred obligation to do as much toward it as possible.
For that is good and acceptable before God - It is a duty everywhere enjoined; compare Matthew 15:5-7 notes; Ephesians 6:1-2 notes.