וַֽיִּשְׁחֲט֖וּ אֶת־הַפָּ֑ר וַיָּבִ֥יאוּ אֶת־הַנַּ֖עַר אֶל־עֵלִֽי׃
Kinatay nila ang toro, at dinala nila ang bata kay Eli.
Rashi
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.
Metzudat David
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.
Radak
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.