Musar su Isaia 58:14

It is also necessary to rejoice on Sabbaths, Festivals and on Purim because all of them are a memorial to our exodus from Egypt and of the miracles which He has done wonderously with His chosen ones. Therefore, shall one rejoice in his heart when he remembers the kindnesses of God and the great extent of his goodness with those who do His will. And for this reason do we prepare tasty foods and precious garments and we drink wine, in order to cause the heart to rejoice. And one must be careful not to rejoice with such joy for frivolous reasons but should rejoice with such rejoicing because of his love for God, may He be Blessed, and delight with this delight of love for the Rock, and he should rejoice and be glad in the joy of the Lord of all, who commanded him to have pleasure in that day and to rejoice. And in these Sabbath and Festival days he should be mindful of the pleasantries of the world to come which is the pleasure of all pleasures. And it is proper for a man at such times when he is enjoying pleasures that he should be mindful of the greater pleasures and desire them, as it is written "Then shalt thou delight thyself in the Lord" (Is. 58:14).