וַיֵּ֨צֶר לְאַמְנ֜וֹן לְהִתְחַלּ֗וֹת בַּֽעֲבוּר֙ תָּמָ֣ר אֲחֹת֔וֹ כִּ֥י בְתוּלָ֖ה הִ֑יא וַיִּפָּלֵא֙ בְּעֵינֵ֣י אַמְנ֔וֹן לַעֲשׂ֥וֹת לָ֖הּ מְאֽוּמָה׃
Labis na nabagabag si Amnon hanggang sa siya'y magkasakit dahil kay Tamar na kanyang kapatid na babae; sapagkat siya'y isang dalaga, at tila imposible kay Amnon na gumawa ng anuman sa kanya.
Rashi
Because she was a virgin. She was modest [and stayed] in the house and did not go outside therefore, "It was hidden from the eyes of Amnon… It was covered and hidden from him. What excuse he could seek [in order] to lay with her.1According to Rashi, the words in our verse, “because she was a virgin” do not tell us why Amnon was desirous of her. The reason for his desire was because she was pretty. Rashi consequently explains that these words are telling us why she was inaccessible to Amnon and are connected to the words that follow, “it was hidden in the eyes of Amnon” to find a way to lay with her. Similar to "When it is concealed from you",2Devorim 17:8. [which] Onkelus translates: "When it is hidden from you."