Reference for Shabbat 184:7
אמר ר' יהודה אני אמרתי דבר אחד והן אמרו דבר אחד אני לא מצאתי תשובה לדבריהם והן לא מצאו תשובה לדברי מדקאמר להו אי אתם מודין לאו מכלל דפטרי רבנן וליטעמיך דקאמרי ליה אי אתה מודה מכלל דמחייב רבי יהודה והתניא לאחר ידו ורגלו ד"ה פטור
it is unnecessary [to rule that if he intended to carry it] behind him and it came behind him, he is culpable, since his intention was fulfilled. But even [if he intends to carry it] BEHIND HIM, BUT IT WORKS ROUND BEFORE HIM, it must be [stated]. [For] you might think that I will rule, since his intention was unfulfilled, he is not culpable; therefore he informs us that he intended [only] a weak vigilance whereas he succeeded [in giving it] a strong vigilance, So that he is culpable. [Shall we say that where he intends to carry it] behind him, and it comes behind him, there is a controversy of Tannaim? For it was taught: If one intends carrying out [an object] in his belt with its opening above, but he carries [it] out in, his belt with its opening below, [or] if one intends to carry out in his belt with its opening below,<span class="x" onmousemove="('comment',' This is the reading in the Tosef. Shab. and is thus emended here by Wilna Gaon. Cur. edd.: If one carries out money in his belt with its opening above he is culpable; if its opening is below, R. Judah rules that he is culpable etc. ');"><sup>12</sup></span>