1 John 2:8-10

Yet, in a sense, it is a new commandment, as its truth is made manifest both in Christ and in you, because the darkness is disappearing and the true light is already blazing. Anyone who says, “I am in the light,” while holding hatred in his heart toward a fellow believer is still in the darkness. But the one who truly loves a fellow believer lives in the light, and there is nothing in him that will cause someone else to stumble.