Albert Barnes Commentary 1 Samuel 1:22

"But Hannah went not up; for she said unto her husband, [I will not go up] until the child be weaned; and then I will bring him, that he may appear before Jehovah, and there abide for ever." — 1 Samuel 1:22 (ASV)

Until the child is weaned - Hebrew mothers, as elsewhere in the East, usually suckled their children until the age of two complete years, sometimes until the age of three.