Again we face here an uneasy word.
Letter ב is likely to be the well known preposition we have already met: in, with.
If so, what about היסמך?
We will not find it in the dictionary.
We will not find it in the dictionary because this is a verbal form, one of the many forms of a conjugation: Niph'al.
Unless your level of Hebrew is high, the best way to get the good meaning and translation of this word is taking a look at Oham: P-t088 and following.
The answer we're seeking for is found in ptr P-t096.A.