John Calvin Commentary Ephesians 4:29

"Let no corrupt speech proceed out of your mouth, but such as is good for edifying as the need may be, that it may give grace to them that hear." — Ephesians 4:29 (ASV)

No filthy speech. He first forbids believers to use any filthy language, including under this name all those expressions that are typically used for the purpose of inflaming lust. Not satisfied with the removal of this vice, he commands them to frame their discourse for edification. In another Epistle he says, Let your speech be seasoned with salt (Colossians 4:6).

Here a different phrase is employed, if any (speech) is good to the use of edifying, which means simply, if it is useful. The genitive, of use, may undoubtedly be viewed, according to the Hebrew idiom, as an adjective, so that for the edification of use (πρὸς οἰκοδομὴν τὢς χρείας) may mean for useful edification. However, when I consider how frequently, and in how extensive a meaning, the metaphor of edifying occurs in Paul’s writings, I prefer the former exposition.

The edification of use will thus mean the progress of our edification, for to edify is to carry forward. To explain the manner in which this is done, he adds, that it may impart grace to the hearers, meaning by the word grace, comfort, advice, and everything that aids the salvation of the soul.