He who says, or ‘When/If a person says,’ introduces the proposition of the false teachers, which is given in direct discourse. Compare the general remarks on 2.3-11.

He … disobeys (literally “does not keep”) his commandments, repeating the last clause of verse 3, but in the negative. The variation “to keep – to disobey” of Revised Standard Version should not be imitated unless clearly required by idiom.

Is a liar (also in 2.22; 4.20), or ‘lies,’ ‘is telling a lie’; see comments on 1.10, and on “we lie” in 1.6.

The truth is not in him. The Greek form rendered in him can also mean “in that,” namely, in that behavior, but the personal meaning is much more likely because of the parallel in 1.8.

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