LEV651 A man must take great care not to rejoice in something which is good for him but injurious to others. So that if one has much grain, he should not rejoice in dearness and famine, and not allow his good to bring him joy through the hardship of others. Nor should he rejoice in a man's death, though he stands to gain an inheritance or other benefits through it. In sum, one must not rejoice in any man's discomfiture for the sake of his pleasure. About this it is said [this verse]: "And you shall love your fellowman as yourself." And one should teach himself to be happy when good befalls others, especially when he sees them pursuing mitzvos to do the will of the Blessed Creator.