Commentary for Psalms 41:4

on his sickbed Heb. ערש, lit in French, as (in Deut. 3:11): “Behold his bed is an iron bed.” When he too takes ill, He will support him. What is the meaning of “on his sickbed”? This is the seventh day of the sickness, when he is very ill. In this manner, it is explained in Aggadath Tehillim (Mid. Ps. 41:5).

when You have transformed his entire restfulness in his illness Even in the time that his illness has become more acute, when all his restfulness and tranquility have been transformed.