Rashi: None of the Kelim were of silver, for silver had no importance
1
.
2.
Yalkut Chadash (David, 64-65): Shlomo considered silver to be worthless, and discarded it. Hashem said, due to this he will need to take [Tzedakah] from people
2
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I.e. when Ashmedai threw Shlomo 400 Parsa'os (about 1600 kilometers), he was left with only his staff (or cloak), and went begging from door to door (Gitin 68b). (PF)