Why does it say "va'Yismach Aleihem"?
Malbim: He was happy Bam (with them), for he knew that they did not come like those who make a Bris, and lovers. Rather, he was happy due to them, for it was an opportunity for him to glorify himself. He was great in Hashem's eyes, and amidst his pride and love of aggrandizement, he glorified himself with is wealth and storehouses, and showed them everything. I.e. not only does Hashem approve of me - I am also successful in wealth, honor and royal treasures.
What is "Beis Nechoso" that he showed to them?
Rashi: It is where fragrances are hidden, like "Nechos u'Tzri va'Lot" (Bereishis 37:25).
Radak (Melachim II, 20:13): It is Beis Chemdaso, i.e. everything [desirable] that he has. Afterwards the verse details what were the desirable things. Also "Nechos u'Tzri va'Lot" (Bereishis 37:25) is something desired.
Radak (Melachim II, 20:13, citing Sanhedrin 104a) #1: His own wife gave them to drink.
Radak (Melachim II, 20:13, citing Sanhedrin 104a) #2: Iron that can shatter iron.
Radak (Melachim II, 20:13 citing Sanhedrin 104a) #3: His treasure house.
What is "Shemen ha'Tov"?
Rashi #1: Some say that it is Shemen ha'Mishchah.
Rashi #2: Some say that it is balsam oil, which is found in Eretz Yisrael - Yehudah v'Eretz Yisrael Hemah Rochlayich b'Chitei Minis u'Fanag" (Yechezkel 27:17). Sefer Yosifun says that Panag is balsam; it grows [Radak Melachim II, 20:13 - only] in Yericho, which is called Yericho due to the Rei'ach (smell).
It already said that he showed everything to them. What does "Lo Hayah Davar..." include?
Rashi: The Sefer Torah (Rashi Melachim II, 20:13 - and the Aron and the Luchos).
