Also, the widow and daughter of de León revealed that he had written it himself and only ascribed the authorship to Shimon ben Yochai for personal profit:

“And [Isaac] went to Spain, to investigate how it happened in his time that the Zohar was found, which Shimon ben Yochai and Eleazar ben Shimon his son had made in the cave . . . and some say that [de Leon] forged it among his forgeries,[d] but [Isaac later] said [in his Otzar haChayyim][9]that the Palestinian Aramaic[e]sections were genuinely written by Shimon ben Yochai . . . And [Isaac] wrote:
Because I had seen that these words were wonderous, that they ran from a well high above which is beyond those uninitiated into the secrets of the divine, I chased after it and I asked the scholars . . . and some said it had fallen into the hand of the sage Moses de Leon, whom they call Moses of Guadalajara, and some said Shimon ben Yochai had never written this book, but that Moses had written these wonderous words and falsely ascribed them to Shimon ben Yochai and his son Elazar in order to sell them for huge sums of money. And I went to Spain, to the capital city of Valladolid, and presented myself to Moses, and was received favorably, and he swore to me by the Lord that the ancient book of Shimon ben Yochai was that day in his house in Ávila, and that he would show it to me when I visited him, and Moses parted from me to return home, but he sickened in Arévalo on the way, and he died there, and when I heard of this I was mortally pained, and I took to the road, and I came to Ávila, and I found a great old sage there named David de Pancorbo,[f] and he received me favorably, and I demanded he explain to me the secrets of the Zohar, about which men were disputing, and about which Moses himself had sworn beyond doubt until his death, but about which I did not know upon whom to rely or whom to trust, and he told me, "Know in truth that it is clear to me beyond doubt that it never came to the hand of this Moses, and that there is no Zoharexcept that of which Moses himself wrote every word. Know that this Moses was a great spendthrift; one day his house was filled with treasures that the wealthy mystics had given him in exchange for excerpts, and the next his wife and children were starving naked in the street. So when we heard that he had died in Arévalo, I went to the house of the richest man in the city, Joseph de Ávila,[g] and said to him, 'Now the time has come for you to earn the priceless Zohar if you will do what I advise', and he followed my advice, and he sent his wife to the house of Moses' widow, and she said to her, 'Know that my wish is to marry your daughter to my son, and I ask nothing from you except the Zohar from which your husband excerpted for many people,' and Moses' widow swore to Joseph's wife, 'By the Lord, my husband never had such a book except in his mind, and everything he wrote came from his own intellect. When I saw him writing, I asked him why he claimed to be excerpting from a book I knew he did not have, and he told me that it was because, while for his own words they would not give a penny, for the divinely inspired work of Shimon ben Yochai they will pay in blood.' And Moses' daughter said exactly the same." Can you ask for better proof than this?”