וַיֹּ֣אמֶר ל֗וֹ מַדּ֣וּעַ אַ֠תָּה כָּ֣כָה דַּ֤ל בֶּן־הַמֶּ֙לֶךְ֙ בַּבֹּ֣קֶר בַּבֹּ֔קֶר הֲל֖וֹא תַּגִּ֣יד לִ֑י וַיֹּ֤אמֶר לוֹ֙ אַמְנ֔וֹן אֶת־תָּמָ֗ר אֲח֛וֹת אַבְשָׁלֹ֥ם אָחִ֖י אֲנִ֥י אֹהֵֽב׃
Er fragte ihn [eines Tages]: Warum bist du so sehr abgezehrt, du Königssohn, einen Morgen mehr als den andern? Willst du es mir nicht sagen? Da sprach Amnon zu ihm: Ich liebe Tamar, die Schwester meines Bruders Awschalom.
Rashi
the poor Heb. דל, the ill, to visit him, as the matter that is stated (in II Sam. 13:4): “Why are you so poor (דל)...?” mentioned in reference to Amnon.
Pat Lechem
needy (dal), poor (ani) -- the sages counted 7 expressions for the poor man (Vayikra Raba BeHar). Each one applies to a specific aspect. The term "dal" (needy) refers to one whose flesh is scant, with little fat, such as "Why are you becoming so thin, O' son of the king" (Samuel II 13:4). The term "ani" applies to his being submitted, such as "How long will you refuse to humble yourself before Me?" (Ex. 10:3).
Ibn Ezra
מדלה With pining sickness. Comp. דל lean (1 Sam. 13:4). With this illness, which I am suffering now,
Rashi
דלות means LEAN, as (2 Samuel 13:4) “Why art thou thus becoming (דל) lean?” which occurs in the narrative of Amnon.