Ephesians 4:21 If indeed you have heard Him and have been taught in Him as the reality is in Jesus, (29) Let no corrupt word proceed out of your mouth, but only that which is good for building up, according to the need, that it may give grace to those who hear.
http://Before he mentions grace here, Paul presents the principle, the pattern, the standard; that is, he presents the truth which is the life of truth in Jesus. We have been placed by God through baptism into the pattern, the standard, the principle, set up by the living of the Lord Jesus on earth. This is the truth in Ephesians 4.
In order to live out such a standard, we must have grace. In verse 29 Paul relates grace to our speaking. This indicates that we need grace for the details of our daily life, not just for what we regard as important matters.
We may have grace in big matters, but not in small matters. For example, a brother may have grace to minister the Word, but he may lack grace in speaking to his wife. Furthermore, in the prayer meeting we may all have grace, but in our daily conversation we may be devoid of grace.
In no area of our daily life do we require grace more than in our conversation. If we have grace in this aspect of our living, we shall have grace in every other aspect. In all things we need grace to live a life according to the truth that is in Jesus and to be molded into the image of Christ.
Grace is our rich supply and enjoyment. If we have this supply and enjoyment, we shall be able to live according to the standard of the principle of truth.