Surely you heard of Him and were taught in Him—in keeping with the truth that is in Jesus—
21. If ye have heard him. To excite their attention and earnestness the more, he not only tells them that they had heard Christ, but employs a still stronger expression, ye have been taught in him, as if he had said, that this doctrine had not been slightly pointed out, but faithfully delivered and explained. As the truth is in Jesus.
The apostle having gone through his exhortation to mutual love, unity, and concord, in the foregoing verses, there follows in these an exhortation to Christian purity and holiness of heart and life, and that both more general (Eph 4:17-24) and in several particular instances, Eph 4:25-32.
Commenting on Ephesians 4:17-32
That ye put off concerning the former conversation, the old man,.... Which is the corruption of nature; why this is called a man, and an old man; see Gill on Rom 6:6, the putting him off, is not a removing him from the saints, nor a destroying him in them, nor a changing his nature; for he remains, and remains alive, and is the same...