Psalms 109:24

My knees are weak through fasting
. Either voluntary or forced, through want of food or refreshment; this was verified in Christ, when he kneeled and prayed, and his sweat was as it were great drops of blood falling to the ground; see ( Psalms 69:10 ) .

And my flesh faileth of fatness;
or "for want of oil" ^F11; the radical moisture of his flesh being dried up like a potsherd, ( Psalms 22:15 ) .