Albert Barnes Commentary 2 John 1:4

"I rejoice greatly that I have found [certain] of thy children walking in truth, even as we received commandment from the Father." — 2 John 1:4 (ASV)

I rejoiced greatly that I found, etc. This means I learned this fact respecting some of your children. The apostle does not say how he had learned this. It may have been that he had become personally acquainted with them when they were away from their home, or that he had learned it from others. The word used (eurhka) would apply to either method. Grotius supposed that some of the sons had come on business to Ephesus, and that John had become acquainted with them there.

Of your children walking in truth. That is, true Christians; living in accordance with the truth, for this constitutes the essence of religion. The expression used here, "of your children," (ek twn teknwn), means some of your children, implying that he knew of a part of them who were true Christians. This is clear from the Greek construction, because:

1. If he had meant to say that he had found them all to be of this description, the sentiment would have been directly expressed, "your children;" but as it is, some word is necessary to be understood to complete the sense; and
2. The same thing is demanded by the fact that the participle used (walking—peripatountav) is in the accusative case. If he had referred to them all, the participle would have been in the genitive, agreeing with the word children (twn peripatountwn). —Lucke.

Whether the apostle means to say that only a part of them had in fact embraced the gospel, or that he had only known that a part of them had done so (though the others might have done it without his knowledge), is not quite clear. However, the former supposition appears to be the correct one, for if they had all become Christians, it is to be presumed that he would have been informed of it.

The probability seems to be that only a part of her children were truly pious, though there is no evidence that the others were otherwise than correct in their moral conduct. If there had been improper conduct in any of her other children, John was too courteous, and too delicate in his feelings, to allude to so disagreeable a circumstance.

But, "if that pious lady," to use the language of Benson, "had some wicked children, her lot was not peculiar. Her consolation was that she had some who were truly good. John commended those who were good, in order to excite them in the most agreeable manner to persevere."

As we have received a commandment from the Father. That is, as He has commanded us to live: in accordance with the truth which He has revealed. The Father, in Scripture, is everywhere represented as the source of law.