מנין שאין הקב"ה מקפח אפילו שכר שיחה נאה שאילו בכירה דקרייה מואב וכו'
Lot's firstborn daughter named her child מואב thus recalling she bore him from her father.
Lot's second daughter named her child בן עמי which do not explicitly recall the child was from her father. For being more discreet than her older sister, she was rewarded.
In the Hakdama to the Igros Moshe (O.Ch.8 ) there is a very interesting story supposedly told by R. Moshe zt"l:
R. Moshe went to be מבקר חולה in Luban a sick person whose tongue had swelled up.
He told R.Moshe the reason why he contacted this disease.
He said he had a קושי'
" משיח How is it, that the
will be an offspring of these women who were not even ashamed to name their children and publicize having relations with their
One day he had a dream
Two elderly women came to him and claimed to be the daughters of Lot. They told him they heard his complaint and wanted to respond.
They said they could have easily claimed that the children were born by an immaculate conception and invent a new religion
They intentionally named them עמון ומואב
(embarrassing themselves) to publicize
that there is no such thing as an immaculate conception.
For this reason they were rewarded that the true
משיח will come from them.
They also told him that he was being punished
for speaking badly about them.
After he finished telling the story to R.Moshe
he turned to the other side and died.