There is a Sefer "תם ומועד" which reportedly says that Yeshu (ימח שמו) was able to perform miracles because he was in the Beis Hamikdash when the Kohen Gadol said the Shem HaMeforash, wrote the name down (because people who heard the Name forgot how to say it shortly afterwards), and used it himself.
Where is this in the תם ומועד (or any other Torah source)?
In Tam U-Muad it says (pg. 15 here):
"ויבא עד לירושלים ואין מכיר בו ויבא אל תוך המגדל בתוך הבאים והי' שם אבן שתי' והוא האבן אשר נסך יעקב אבינו ע"ה שמן על ראשה. ועל האבן ההיא הי' חקוק שם המפורש. ומי שהי' למד אותו וידע סודו ולסדרו אח"כ על הקלף כשר ושמו בחיקו הי' בידו לשדד המערכות ולהחיות מתים ולעשות כל מה שלבו חפץ. ועלתה בידו לכבוד שם הקדוש והנורא אשר שם בחיקו...
והרשע הזה בהיותו בבה"מ רשם לו סדר שם המפורש על הנייר בעט ברזל שהי' מוכן בידו מן החקיקה. וקרע את בשרו באיזמל ולא הרגיש בשרו בקריעת האיזמל מחמת קדושת השם שבידו. ואת הנייר שם בתוך הקרע ויסגור בשר תחתינה..."
Translation: "And he came to Yerushalayim and no one recognized him and he came into the tower among all of the arrivals, and there was the Foundation Rock, which was the rock upon which Yaakov Avinu, peace be upon him, poured oil atop its head. And upon that rock the True Name was inscribed. And whosoever learned it and its secret and the way to form it correctly upon a scroll and would put it in his lap it is within his power to utterly change the frameworks [of creation] and awaken the dead and do anything that his heart desires. And this is possible due to the Holy and Terrible Name that he put in his lap...and that wicked man when he was in the Temple wrote down the form of the True Name on a paper with an iron pen that was prepared in his hand from the inscribing. And he tore his flesh with a peg and his flesh did not feel the tearing by the peg due to the Holiness of the Name that was in his hand. And he put the paper in the torn area and closed the flesh over it..."
And then he goes on to perform miracles.
