1Sa 1:21-22
When Elkanah went up again with his family to Shiloh, to present his yearly sacrifice and his vow to the Lord, Hannah said to her husband that she would not go up till she had weaned the boy, and could present him to the Lord, that he might remain there for ever. הימים זבח, the sacrifice of the days, i.e., which he was accustomed to offer on the days when he went up to the sanctuary; really, therefore, the annual sacrifice. It follows from the expression “and his vow,” that Elkanah had also vowed a vow to the Lord, in case the beloved Hannah should have a son. The vow referred to the presentation of a sacrifice. And this explains the combination of את־נדרו with לזבּח.
Weaning took place very late among the Israelites. According to 2 Macc. 7:28, the Hebrew mothers were in the habit of suckling their children for three years. When the weaning had taken place, Hannah would bring her son up to the sanctuary, to appear before the face of the Lord, and remain there for ever, i.e., his whole life long. The Levites generally were only required to perform service at the sanctuary from their twenty-fifth to their fiftieth year (Num 8:24-25); but Samuel was to be presented to the Lord immediately after his weaning had taken place, and to remain at the sanctuary for ever, i.e., to belong entirely to the Lord. To this end he was to receive his training at the sanctuary, that at the very earliest waking up of his spiritual susceptibilities he might receive the impressions of the sacred presence of God. There is no necessity, therefore, to understand the word גּמל (wean) as including what followed the weaning, namely, the training of the child up to his thirteenth year (Seb. Schmidt), on the ground that a child of three years old could only have been a burden to Eli: for the word never has this meaning, not even in 1Ki 11:20; and, as O. v. Gerlach has observed, his earliest training might have been superintended by one of the women who worshipped at the door of the tabernacle (1Sa 2:22).