2 John 1:4

I rejoiced greatly that I found of thy children
Not all, but some of them; for good parents have not always good children, or at least not all of them; Adam had a Cain, Abraham an Ishmael, and Isaac an Esau: God is pleased to show his discriminating grace in tribes and families, by taking some, and leaving others: it is a great mercy when any are called by grace, and instead of the fathers are the children: and this was the case of some of the children of this elect lady, they were

walking in the truth:
in Christ, the truth, by faith, as they had received him; and in the truth of the Gospel, as they had embraced and professed it; they abode in it, and by it, and made a proficiency in the knowledge of it, which may be signified by walking, that being a progressive action: as also they walked according to it, and as became it; and likewise they walked in the truth of Gospel worship, discipline, and ordinances:

as we have received a commandment from the Father;
and which has been made known by Jesus Christ, as his mind and will. Now as it is matter of joy and gladness to godly parents when their children walk in the paths of faith, truth, and holiness, so it is also to ministers of the Gospel, as well as to the angels in heaven; it gives them an inward pleasure and joy, and which is not only expressed by them, to such children and their parents, but is also abundant by many thanksgivings unto God.