Vayeira

When Avraham sees the travelers coming toward him, he runs outside and asks them not to pass by his house without coming in. Rather, he says: יקח נא מעט מים ורחצו רגליכם והשענו תחת העץ , take a little water, wash your feet and recline under the tree.

Rashi explains the purpose of washing their feet was to keep idolatry out of his tent since he thought they were Arabs who worshiped the sand.
Rashi continues & says that's unlike Lot who didn't care about having idols in his house, so he says to the Malachim: first come in & rest & then wash your feet.
However, Rashi’s actual explanation when the Malachim came to Lot, was that Lot was scared of the people of Sodom so he had them come in, rest and then wash. If the people came & saw that he had guests who had already washed, they would think that he had had guests for a few days already. Therefore, he didn't have them wash so it should look like they just came. It wasn't that he didn't care about bringing an idol into his house; rather he was afraid for his life.  

If that's true then why does Rashi in the first posuk mention it as a negative of Lot when the reason he did it was just to protect himself. Had there been no fear of the people he would have had them wash first.

The צהר לתיבה relates a story that happened to רבי לוי יצחק מברדיטשוב , who was traveling when he came to the town of Levov & needed a place to sleep for the night. He went to the home of a respected wealthy man & asked for a place to stay for the night, without identifying himself. The man told him, “I don't have room for travelers; go to the local inn. רבי לוי יצחק asked again, pleading, “please don't you have a small room for me; I won't bother you for anything else?” Again, the man answered, “I don't have room. However, if you don't want to go to the inn, you can go to the schoolteacher on the next block who takes in travelers.”

Having no choice, רבי לוי יצחק went to the home of the schoolteacher where he was received with open arms. Once he was there, someone recognized him & the word spread around town that רבי לוי יצחק מברדיטשוב was in town. Within a short while, all the townspeople, including the wealthy man, were converging on the home of the schoolteacher to greet the great rabbi.

When the wealthy man approached him, he said,  “please forgive me; I didn't know who you were. Please come be my guest, as all the rabbis who come to town stay at my house.

The rabbi answered him with a question, what was the difference between Avraham & Lot ? Why is Avraham known for his hospitality while Lot is not? When the Malachim came to them, both prepared a big meal for them so why isn't Lot known for his hospitality like Avraham?

He explained that the wording of the Posuk shows the difference. By Lot it says, ויבאו שני המלאכים the two angels came, & that's when he was hospitable whereas by Avraham it says, שלשה אנשים נצבים עליו three men were coming toward him. Lot saw angels & therefore welcomed them into his home while Avraham saw ordinary people, tired and covered in dust & begged them not to pass by his home.   

Maybe this is the difference between the two Rashis. In the first one, Rashi is critical because the posuk was talking about the travelers as people, so Lot should have had them wash not to bring avodah zara into his home. However, in the second Rashi, they were identified as Malachim so there was no reason to suspect idol worship. Therefore, Rashi gives a separate reason why he didn't have have them wash first.

Continued רבי לוי יצחק, as children of Avraham, we have to emulate his ways & not the ways of Lot.
Teaching us that we have to help out all kinds of people. We have to be hospitable, friendly, helpful to everyone not just those that are respected or wealthy but the downtrodden & weary too showing that we are truly the children of Avraham Avinu!