מדרש על אסתר 5:13

Another explanation: "He who walketh with wise men shall be wise" (ibid.). This refers to Lot, who walked with our father Abraham, and learned of his good deeds and ways. They said: What did our father Abraham do? He made for himself a house opposite to Haran, and he received everyone who entered into or went out from Haran, and he gave him to eat and to drink. He said to them: Say ye, The God of Abraham is the only one in the universe. || When Lot came to Sodom he did likewise. When they made proclamation in Sodom: All who strengthen the hand of the poor or needy with a loaf of bread shall be burnt by fire, he was afraid of the men of the city, (and did not venture) to do so by day, but he did it by night, as it is said, "And the two angels came to Sodom at even; and Lot sat in the gate of Sodom" (Gen. 19:1). Why did Lot sit in the gate of Sodom? Because he was afraid of the men of the city, (and did not venture) to act (charitably) by day, but he did so by night. He saw the two angels walking in the street of the city, and he thought that they were wayfarers in the land, and he ran to meet them. He said to them: Come and lodge ye overnight in my house, eat and drink, and ye shall go your way in peace. But the men would not accept this for themselves, and he took them by the hand against their will, and brought them inside his house, as it is said, "And he urged them greatly" (Gen. 19:8).