Allah the Exalted says: “O you who believe! Why do you say what you do not do? It is most hateful in the sight of Allah that you say what you do not do.” (Al-Saff 2–3)

[Explanation]
“O you who believe”—He addresses them by their very faith, because true faith requires a person not to behave in this manner and never to say what he does not practice. He then reproaches them, saying, “Why do you say what you do not do?” After that He makes clear that such conduct is detested by Him in the strongest terms: “It is most hateful in the sight of Allah that you say what you do not do.” The scholars explain that al-maqt is the most intense form of hatred. Thus Allah hates the person whose condition is that he speaks but does not act. By informing His servants of this, He intends that they keep well away from it, for the genuine believer distances himself from whatever Allah has forbidden.

Concerning Shuʿayb, He says: “I do not desire to differ from you in that which I forbid you” (Hud 88). In other words, he is telling his people, “It is impossible for me to forbid you from wrongdoing—from cheating in measure and weight—then practice it myself. That can never be,” for the messengers—peace be upon them—are the most sincere of all creation toward creation; they revere Allah most, comply with His commands most perfectly, and avoid His prohibitions most scrupulously. It is unthinkable that they would fall into what they have forbidden others.

This shows that anyone who perpetrates what he forbids, or neglects what he has been commanded, is acting contrary to the way of the messengers, peace be upon them, for they would never do the very things they tell people to avoid. The forthcoming hadiths, God willing, will clarify the punishment awaiting those who abandon what they were commanded or commit what they were forbidden. Allah alone grants success.