Commentary for Genesis 40:3

מקום אשר יוסף אסור שם, the Torah had to write this so that we understand how these prisoners came to tell Joseph their dreams, the dreams which became instrumental in Joseph being released from prison, eventually. The word מקום here is in a construct mode to the word אשר. Hence we have only a sheva under the letter מ instead of the full vowel kametz. Similar constructions are found in Job 18,21 מקום לא ידע א-ל, “a place for people who did not know G’d. (no kametz under the מ in the word מקום. The same applies to Isaiah 8,6 ומשוש את רצין, where the word משוש does not have the vowel kametz under the letter מ as it is in a construct mode to רצין בן רמליהו.

מקום אשר יוסף אסור שם, “the place where Joseph was kept imprisoned.” All of these “coincidences” were designed to bring about the descent to Egypt by Yaakov and his family in accordance with the prediction in Genesis 15,13 “for your descendant will be a stranger, etc.” [without overt interference with the free choice of either party. Ed.]

במשמר. Auch bei מקושש ist משמר nur eine Untersuchungshaft. Im Hause des Fürsten der Köche war ein Gefängnis. Ihm wurden sie anvertraut. Er konnte sie, wo ihm beliebt, bewahren. Siehe oben zu Raw Hirsch on Genesis 40: 20.

ויתן אותם במשמר בית שר הטבחים, “He placed them under protective custody in the house of the chief of the executioners.” This was the customary place where prisoners whose crime carried the death penalty if proven guilty would be placed pending judgment.