Do you realize the similarity of this word to word number 20?
Letter ל is the preposition that means to, for. And, the same as in word 20, הישאר is the Niph'al Infinitive construct of verb שָׁאַר, to remain, be left over. Look at 1Sa 16:11.
The answer we're seeking for is found in ptr P-t096.A.
Then, to be remained, be left over.