בראשית מ:ד פירוש: רש״י, רשב״ם, רד״ק ורבנו בחיי

ויפקד שר הטבחים את יוסף AND THE OFFICER OF THE EXECUTIONERS APPOINTED JOSEPH — to be WITH THEM (i.e. supply the word להיות to complete the sense).

ויפקד שר הטבחים, he appointed him to look after all the needs of the various prisoners in that jail.

ויפקוד, he appointed Joseph to be their constant companion and personal valet. We are told this so that we can understand why Joseph enjoyed their confidence and they told him their dreams.