Jacob's blessing, Genesis 49

"Asher's bread shall be rich
And he shall yield royal dainties."

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Mose's blessing, Deuteronomy 33,

Most blessed of sons be Asher,
May he be the favorite of his brothers,
May he dip his foot in oil.

May your doorbolts be iron and copper,
And yout security lass all your days

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Midrash Rabbah Bamidbar 2

His gem was aqua-marine (Tahrshish).
His color was like a precious stone used by women for decoration.
There was an olive tree drawn on it.

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Asher
The precious olive oil is the main motive here. The background color of the Window ressembles the dark grey-green coloration of the olive tree.

There is a the olive tree itself, at the right side, a bird-like shaped oil vessel at the left bottom corner,

The Menora (seven-branched candelabrum, one of the most sacred objects in the Sanctuary) was fed by pure olive oil, and therefore it appears at the bottom of the window. A cup used to feed the menora with oil, is shown next to it from the right side.

The dove with an olive branch in her beak , the eternal symbol of peace, is shown at the top.