Midrasz do Izajasza 19:8

(Fol. 30) R. Jochanan, in the name of R. Simon b. Jochai, said: "What is the meaning of the passage (Is. 19, 8) For I, the Lord, love justice; I hate robbery with burnt-offering. Unto what may this be compared? Unto a frail king, who passed the custom-house and said to his servants: 'Pay the duty to the officers;' and the servants said to him: 'O King, our master, why shall we pay duties? Are not all the duties thine!' Whereupon the king said: 'All the travelers shall take a lesson from me, and shall not try to smuggle their duty.' So said also the Holy One, praised be lie! I, the Lord, hate robbery with a burnt-offering; i.e., of Me shall my children learn, and avoid robbery." We are also taught that R. Ami said: "A dry lulab is invalid because you cannot call it beautiful [as prescribed by Law], and a lulab acquired by robbery is invalid, because it is a religious object acquired through a wrong deed [which is always illegal]."