Reference for Bava Metzia 172:21
מאי שנא לגבי אברהם דכתיב (בראשית יח, ה) כן תעשה כאשר דברת ומאי שנא לגבי לוט דכתיב
But is it not written, <i>And there came the two angels to Sodom at even</i>?<span class="x" onmousemove="('comment',' Gen. XIX, 1. ');"><sup>38</sup></span> — Michael accompanied him to rescue Lot. [The Writ] supports this too, for it is written, <i>And</i> he <i>overthrew those cities</i>,<span class="x" onmousemove="('comment',' Ibid. 25. ');"><sup>39</sup></span> not, and <i>they</i> overthrew: this proves it. Why is it written in the case of Abraham, [<i>And they said</i>,] <i>So do, as thou hast said</i>;<span class="x" onmousemove="('comment',' Ibid. XVIII, 5: they immediately accepted the invitation. ');"><sup>40</sup></span> whereas of Lot it is written,