Commentary for Kiddushin 141:11
רבי אבינא רמי כתיב (שמות ג, טו) זה שמי וכתיב (שמות ג, טו) זה זכרי אמר הקב"ה לא כשאני נכתב אני נקרא נכתב אני ביו"ד ה"י ונקרא באל"ף דל"ת
Our Rabbis taught: At first [God's] twelve-lettered Name<span class="x" onmousemove="('comment',' V. n. 6 [This would suggest that they also hesitated to write or pronounce this latter name in full, but wrote or pronounced it merely Ad or Alef dateth. Lauterbach. J.Z. Proceedings of the Americas Academy for Jewish Research 1930-1931. p. 43.]');"><sup>26</sup></span> used to be entrusted to all people. When unruly men increased,<span class="x" onmousemove="('comment',' And it was not fit that they should pronounce this.');"><sup>27</sup></span> it was confided to the pious of the priesthood,<span class="x" onmousemove="('comment',' [To utter it at the priestly benediction, v. Sot. 38a.]');"><sup>28</sup></span>