John Gill Commentary Genesis 44:29

"and if ye take this one also from me, and harm befall him, ye will bring down my gray hairs with sorrow to Sheol." — Genesis 44:29 (ASV)

And if you take this also from me His son Benjamin, as he perhaps suspected they had taken Joseph, and made away with him:

and mischief befall him ; either in Egypt, or on the road, going or returning, any ill accident, especially death, as the Targums of Onkelos and Jonathan, or what may issue in it:

you shall bring my gray hairs with sorrow to the grave ; it would be the means of his death, and while he lived he should be full of sorrow and grief; see (Genesis 42:38) .