John Gill Commentary 1 Samuel 9:20

"And as for thine asses that were lost three days ago, set not they mind on them; for they are found. And for whom is all that is desirable in Israel? Is it not for thee, and for all thy father`s house?" — 1 Samuel 9:20 (ASV)

And as for your asses that were lost three days ago
Which, according to Kimchi, is to be understood not of the time from which they were lost, but to be reckoned from the time that Saul had been seeking of them; so the Targum, ``as to the business of the asses, which are lost to you, and you are come to seek them today, these three days:'' though it is probable enough that the same day they were lost Saul set out to seek them. Now Samuel telling him of the asses that were lost, and of the time of their being lost, or of his seeking them, so exactly, before ever he said a word to him about them, must at once convince him that he was a true prophet, and which must prepare him to give credit to all that he should hereafter say to him:

set not your mind on them, for they are found ;
of the truth of which he could not doubt, after he had said the above words; and which he said to make his mind easy, that he might the more cheerfully attend the feast, and be the more willing to stay all night:

and on whom is all the desire of Israel ?
which was to have a king; in this they were unanimous, and who so fit and proper as Saul, it is intimated, whom Samuel knew God had chosen and appointed to be king over them?

is it not on you, and on all your father's house ?
not that the Israelites had their eye on Saul, and their desire after him to be their king, though he was such an one as they wished for; but that as this desire of theirs was granted, it would issue and terminate in him and his family; he should be advanced to the throne, which would be attended with the promotion of his father's house, as Abner particularly, who was his uncle's son, and was made the general of the army.