Verses 3 and 4, linked to what precedes by the connective For, give the reason why the writer is confident that all is well with Gaius’ soul. Accordingly the verses are to be taken as belonging to the opening part of the Letter.

For I greatly rejoiced see comments on 2 John 4.

When some of the brethren arrived: the verb form is in the present tense, showing that the reference is to repeated visits, as brought out by ‘every time when some of our brothers came here,’ ‘that again and again some brothers arrived.’ The brothers mentioned probably were preachers who had been sent out by the congregation of “the elder,” had visited the congregation of Gaius, and on their return had reported to the home church.

The brethren, or “the brothers,” is used also in verses 5 and 10. For the translation of “brother” see comments on 1 John 2.9.

Testified to the truth of your life: for the verb testified, compare comments on 1 John 1.2; it means that they spoke of what they had seen, heard, and experienced of Gaius. In this context it can often be simply rendered as ‘told about.’

The truth of your life is in the Greek literally “your truth” (paralleling “your love” in verse 6). The noun truth refers to a behavior that is in accordance with God’s will, and to a life that is lived in close relationship with God; compare comments on 1 John 1.6. Some other possible renderings are ‘that you are truly devoted to God,’ ‘your being a man who is straight-hearted,’ or “how faithful you are to the truth” (Good News Translation).

As indeed you do follow the truth: the Greek connective used may serve to introduce an indirect discourse. Then the clause is to be taken as giving the contents of what the returning brothers had said, “namely, that you follow the truth.”

Another meaning of the connective is that it indicates reason and serves to reinforce the preceding statement. To bring this out Revised Standard Version has added indeed. Then the clause parallels verse 2b and states that the testimony John received was in accordance with what he knew about Gaius.

You is emphatic. It serves to bring out a contrast between the behavior of Gaius and that of Diotrephes (verses 9-10). For “to follow the truth,” in the Greek literally “to walk in truth,” see comments on 2 John 4.

Quoted with permission from Haas, C., de Jonge, M. and Swellengrebel, J.L. A Handbook on The Third Letter of John. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .