Explaining the Vastness of the Mercy of Allah the Exalted

The Shaykh : Inform him that the mercy of Allah is vast and that His mercy precedes His wrath. And I say to you all: what do you say about the intentional killing of a believer? Is it forbidden or not? Is it forbidden or not forbidden?
The student: It is forbidden.

The Shaykh : Good. And yet, Allah named the killer the brother of the one killed; He called him his brother. Where is the evidence? The saying of Allah the Exalted: Complete it. The killer committed a major sin from the major sins, a great one, and Allah the Exalted named the killer the brother of the one killed. Another example: What is it? "Indeed, and they are fighting, some of them bearing weapons against others, and we are making peace between them, and they are our brothers. Which is greater, smoking or fighting a believer? Fighting a believer and killing a believer. For this reason, I also urge our brothers to know that a person loves something and hates something. We answer the mu'adhdhin; we answer the mu'adhdhin, yes, we answer the mu'adhdhin. I say: O Allah, Lord of this perfect call and the established prayer, grant Muhammad the intercession and the excellence, and raise him to the praised station which You have promised him. Indeed, You do not break Your promise.