Комментарий к Шмуэль А 1:25

They brought the child to Eili. To show that his prophecy was fulfilled. Our Sages expounded what they expounded, explaining that he [Shmuel] ruled on a point of law, that a kohein is not necessary for sacrificial slaughter, as it is stated in [Maseches] Berachos.⁴³ 31b.

And they slaughtered, etc.: Meaning to say, when they slaughtered the first bull, they brought the lad to Eli to show him that his prayer was accepted.

They brought the boy: After they slaughtered the bull for a sacrifice, Elkanah and Channah brought the boy to the House of the Lord to Eli, to reside and study before him; and that [Eli] should educate him about all the Torah and the commandment[s]. And there is no reason to write the homiletical teaching, as it is well-known and it is remote.