Deceit is in the heart of them that imagine evil; i.e. that give evil advice; such are treacherous counsellors, and their advice can only work mischief, not joy and comfort (see on Proverbs 3:29). But to the counsellors of peace (health and prosperity) is joy.
They who give wholesome advice diffuse joy around. Vulgate, "Joy attends them;" Septuagint, "They shall be glad;" but the original signifies rather to cause joy than to feel it.