What is "Yerach Bul"?
Rashi: It is Cheshvan 1 , when grass withers in the field, and people are Bolel 2 for animals from the house - "va'Yaval la'Chamorim" (Shoftim 19:21).
Radak: It is Cheshvan, the eighth month. It is called so, for rain, which can bring a Mabul (flood), begins then.
Radak citing Yerushalmi Rosh Hashanah 1:2: It is Cheshvan, in which a leaf is Naval (falls off the tree), the land become Bulos Bulos (fragmented), and people are Bolel for animals from the house. (Refer to 6:38:1:1**.)
Gra: It received the name Cheshvan after Yisrael descended to Bavel.
Radak (Shoftim 19:21): They mix barley and oats, or one of them with straw. Korban ha'Edah (Yerushalmi Rosh Hashanah 1:2) - they give to them Yevul (yield of the land).
Here it says that the Bayis was finished in the eighth month. Below (8:65) it implies that it was before Sukos, and it says (Mo'ed Katan 9a) that they feasted that Yom Kipur (the day after the Bayis was finished)!
Gra: The building itself finished in Tishrei. Other matters needed for the Bayis were not finished until Cheshvan - "l'Chol Devarav."
Why did the verse need to say that he built it for seven years? We know when he began and when he finished!
Radak: This teaches that he was not lazy. He engaged in building it all seven years.
Gra: This teaches that we do not count the fourth year, in which he began 1 .
Malbim: (a) This teaches the connection to seven - he built it for seven years and seven months. I say that seven years were for building, and after that, seven months to cover it with gold. (b) This was opposite to nature. People seed in Cheshvan, and 'birth' (crops ripen) is in Iyar - here he began in Iyar and finished in Cheshvan! The Divine is complementary to nature - one begins when the other ceases to give birth (produce).
Really, he built for seven years and seven months. The verse calls it seven years, for it does not count a partial year like a full year.
